Debt Disclosure [Abstract] Debt Debt Disclosure [Text Block] Investments, Debt and Equity Securities [Abstract] Held-to-Maturity Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Recipient [Axis] Award Recipient [Axis] Award Recipient [Axis] Award Recipient Type [Domain] Award Recipient Type [Domain] [Domain] for Award Recipient Type [Axis] Employees, officers, and directors [Member] Employees, officers, and directors [Member] Employees, officers, and directors [Member] Advisors and Financial Institutions [Member] Advisors and Financial Institutions [Member] Advisors and financial institutions. Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Stock options and warrants [Member] Stock options and warrants [Member] Stock options and warrants [Member] Restricted Stock [Member] Restricted Stock [Member] Restricted stock awards [Member] Restricted stock awards [Member] Share awards for directors that an entity has not yet issued because the agreed-upon consideration, such as employee services, has not yet been received. Restricted stock units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Expiration period Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Authorized shares Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Authorized unissued shares Share Based Compensation Arrangement By Share Based Payment Award Shares Reserved Share based compensation arrangement by share based payment award shares reserved. Share-based compensation: Share-based Compensation [Abstract] Share-based compensation Allocated Share-based Compensation Expense Share-based compensation cost unrecognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Non-vested compensation cost weighted-average period Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Accounting Policies [Abstract] Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Reportable Segment Segment Reporting, Policy [Policy Text Block] Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Recently Issued Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Earnings Per Share [Abstract] Antidilutive securities excluded from computation of Earnings per Share amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Summary of amortized cost, gross unrealized gain (loss), and fair value of securities held-to-maturity Held-to-maturity Securities [Table Text Block] Maturities of securities held-to-maturity Investments Classified by Contractual Maturity Date [Table Text Block] Document and Entity Information [Abstract] Entities [Table] Entities [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Schedule of Held-to-maturity Securities [Table] Schedule of Held-to-maturity Securities [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Debt Security [Axis] Major Types of Debt Securities [Domain] Major Types of Debt Securities [Domain] U.S. government notes US Treasury Securities [Member] Schedule of Held-to-maturity Securities [Line Items] Schedule of Held-to-maturity Securities [Line Items] Summary of amortized cost, gross unrealized (loss) gain and fair value of securities held-to-maturity Held-to-maturity Securities [Abstract] U.S. government notes - at amortized cost, Total Held-to-maturity Securities Gross unrealized gain Held-to-maturity Securities, Accumulated Unrecognized Holding Gain Gross unrealized loss Held-to-maturity Securities, Accumulated Unrecognized Holding Loss U.S. government notes - at fair value, Total Held-to-maturity Securities, Fair Value Brokers and Dealers [Abstract] Net Capital and Regulatory Requirements Brokers and Dealers Disclosure [Text Block] Summary of Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Weighted-average assumptions used for calculating the fair value of stock options and warrants with the Black-Scholes valuation model Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary of stock option and warrant activity Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of outstanding stock options and warrant information Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block] Summary of restricted stock awards and restricted stock units activity Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Secured Debt [Member] Secured Debt [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Term Loan A [Member] Term Loan A [Member] Term Loan A of Credit Agreement entered into on March 29, 2012 [Member] Term Loan B [Member] Amended Term Loan B [Member] Amended Term Loan B of Credit Agreement entered into on May 13, 2013 [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility [Member] Revolving Credit Facility [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Eurodollar Rate [Member] Eurodollar [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Line of credit, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Interest rate terms of senior secured term loans Debt Instrument, Interest Rate Terms Applicable interest rate margin Debt Instrument, Basis Spread on Variable Rate Letters of credit, amount outstanding Letters of Credit Outstanding, Amount Statement [Table] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Receivables from clients [Member] Receivables from clients [Member] Receivables from clients for amounts due on cash and margin transactions [Member] Receivables from others [Member] Receivables from others [Member] Receivables from others consisting primarily of other accrued fees from product sponsors and advisors [Member] Advisor Loans [Member] Advisor Loans [Member] Advisor Loans [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Statement, Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Statement [Line Items] Statement [Line Items] Allowances on receivables Allowance for Doubtful Accounts Receivable Accumulated depreciation and amortization, Fixed assets Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Unamortized Debt issuance costs Accumulated Amortization, Debt Issuance Costs Accumulated amortization, Intangible assets Finite-Lived Intangible Assets, Accumulated Amortization Debt Issuance Costs, Net Debt Issuance Costs, Net Common stock, par value Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Treasury stock, shares Treasury Stock, Shares Allocated Share-based Compensation Expense Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Number of Shares, Beginning Balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Number of Shares, Granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Number of Shares, Vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Number of Shares, Forfeited Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Number of Shares, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Weighted-Average Grant-Date Fair Value, Beginning Balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Weighted-Average Grant-Date Fair Value, Granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-Average Grant-Date Fair Value, Vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Weighted-Average Grant-Date Fair Value, Forfeited Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Weighted-Average Grant-Date Fair Value, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Number of Operating Segments Number of Operating Segments Number of Reportable Segments Number of Reportable Segments Stockholders' Equity Note [Abstract] Class of Treasury Stock [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] January 2016 [Member] January 2016 [Member] January 2016 [Member] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Stock Repurchase Program, Number of Shares Authorized to be Repurchased Stock Repurchase Program, Authorized Amount Amount Remaining at September 30, 2016 Stock Repurchase Program, Remaining Authorized Repurchase Amount Shares Purchased Treasury Stock, Shares, Acquired Weighted-Average Price Paid Per Share Treasury Stock Acquired, Average Cost Per Share Total Cost Treasury Stock, Value, Acquired, Cost Method Income Statement [Abstract] Statement [Table] REVENUES: Revenues [Abstract] Commission Brokerage Commissions Revenue Advisory Investment Advisory Fees Asset-based Asset Based Fees Revenue recognized in the period for fees from cash sweep programs, sponsorship programs, omnibus processing and networking services. Transaction and fee Transaction And Other Fees Revenue recognized in the period from transaction fees and ticket charges, subscription fees, IRA custodian fees, contract and license fees, conference fees and small or inactive account fees. Interest income, net of interest expense Interest Income (Expense), Net Other Other Income Total net revenues Revenues EXPENSES: Operating Expenses [Abstract] Commission and advisory Commissions And Advisory Fees Gross commissions and advisory fees that are earned and paid out to customers based on the sale of various products and services, production bonuses for achieving production levels, share-based compensation expense for stock options and warrants granted to customers, and deferred commissions for customers as part of a non-qualified deferred compensation plan. Compensation and benefits Labor and Related Expense Promotional Promotional Expenses The total expense recognized in the period for promotional items and business development costs. Depreciation, Depletion and Amortization Depreciation, Depletion and Amortization Amortization of Intangible Assets Amortization of Intangible Assets Occupancy and equipment Occupancy, Net Professional services Professional Fees Brokerage, clearing and exchange Floor Brokerage, Exchange and Clearance Fees Communications and data processing Communications and Information Technology Restructuring charges Restructuring Charges Other Other Expenses Total operating expenses Costs and Expenses Non-operating interest expense Interest Expense, Subordinated Notes and Debentures INCOME BEFORE PROVISION FOR INCOME TAXES Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest PROVISION FOR INCOME TAXES Income Tax Expense (Benefit) NET INCOME Net Income (Loss) Attributable to Parent EARNINGS PER SHARE (NOTE 11) Earnings per share, basic Earnings Per Share, Basic Earnings per share, diluted Earnings Per Share, Diluted Weighted-average shares outstanding, basic Weighted Average Number of Shares Outstanding, Basic Weighted-average shares outstanding, diluted Weighted Average Number of Shares Outstanding, Diluted Basic and diluted earnings per share computations Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Schedule of non-deliverable foreign currency contracts Schedule of Derivative Instruments [Table Text Block] Schedule of the fair value of the derivative instruments Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Stockholders' Equity Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Fair Value, Inputs, Level 1 [Member] Debt Security [Axis] Maturities of securities held-to-maturity Held-to-maturity Securities, Debt Maturities [Abstract] U.S. government notes - at amortized cost, Within one year Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount U.S. government notes - at amortized cost, After one but within five years Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount U.S. government notes - at amortized cost, After five through ten years Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount U.S. government notes - at fair value, Within one year Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value U.S. government notes - at fair value, After one but within five years Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value U.S. government notes - at fair value, After five through ten years Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value U.S. government notes - at fair value, Total Organization, Consolidation and Presentation of Financial Statements [Abstract] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Lpl Financial Llc [Member] Lpl Financial Llc [Member] LPL Financial LLC Ptc Holdings Inc [Member] Ptc Holdings Inc [Member] PTC Holdings Inc. Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Ownership Interest Percentage In Subsidiary Ownership Interest Percentage In Subsidiary Ownership interest percentage in subsidiary. Number of States in which Entity Operates Number of States in which Entity Operates Leases, Operating [Abstract] Rent expense, operating leases Operating Leases, Rent Expense, Net Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Axis] Exercise Price Range [Axis] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] $18.04 - $23.02 Range Two [Member] Range Two. $23.41 - $30.00 Range Three [Member] Range Three. $31.60 - $32.33 Range Four [Member] Range Four. $34.01 - $39.60 Range Five [Member] Range Five. $42.60 - $54.81 Range Six [Member] Range Six. Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Summary information about outstanding stock options and warrants Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, End of Period [Abstract] Total number of shares, Outstanding Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options Weighted-average remaining life (years), Outstanding Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term Weighted-average exercise price, Outstanding Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price Number of shares, Exercisable Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options Weighted-average exercise price, Exercisable Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Summary of share repurchase program activity Class of Treasury Stock [Table Text Block] Dividends Declared [Table Text Block] Dividends Declared [Table Text Block] Concentration Risk Credit Risk Financial Instruments Off Balance Sheet Risk [Abstract] Concentration risk credit risk financial instruments off balance sheet risk. Financial Instruments with Off-Balance-Sheet Credit Risk and Concentrations of Credit Risk Concentration Risk Credit Risk Financial Instruments Off Balance Sheet Risk [Text Block] Description of financial instruments, excluding certain derivatives, with off-balance sheet credit risk (for example, standby letters of credit or financial guarantees), including (1) information about the (shared) activity, region or economic characteristic that identifies the concentration, (2) the face or contract amount of the instrument, (3) the nature and terms of the instrument, including the market risk, cash requirements and accounting policies for it, (4) the maximum amount of loss due to credit risk that would be incurred if the counterparties failed completely to perform according to the terms of the contracts, and any security or collateral that proved to be of no value, (5) the entity's policy of requiring collateral or other security to support financial instruments subject to credit risk, information about access to collateral or other security, and a brief description of the security supporting those financial instruments, and (6) the policy of entering into and a brief description of master netting arrangements to mitigate the credit risk, and the extent to which such arrangements would reduce the maximum amount of loss due to credit risk. Line of Credit Facility [Table] Line of Credit Facility [Table] Lender Name [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Line of Credit [Member] Line of Credit [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Line of credit, amount outstanding Long-term Line of Credit Total number of uncommitted lines of credit Number Of Uncommitted Lines Of Credit Number of uncommitted lines of credit mainted by the Company. Number of uncommitted lines of credit with an unspecified limit Uncommitted lines of credit, unspecified limit The number of uncommitted lines of credit with an unspecified limit maintained by the Company. Line of Credit Facility, Average Outstanding Amount Line of Credit Facility, Average Outstanding Amount Uncommitted lines of credit, utilized Uncommitted lines of credit, utilized Uncommitted lines of credit, utilized Debt Instrument, Interest Rate During Period Debt Instrument, Interest Rate During Period Line of Credit Facility, Expiration Date Line of Credit Facility, Expiration Date Income Tax Disclosure [Abstract] Federal statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Income Tax Benefit Income Tax Benefit The net tax benefit of tax credits and tax deductions, that are not expensed for financial purposes, resulting from software development costs. Derivative [Table] Derivative [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Cash Flow Hedge 1 [Member] Cash Flow Hedge 1 [Member] Cash Flow Hedge 1 [Member] Cash Flow Hedge 3 [Member] Cash Flow Hedge 3 [Member] Cash Flow Hedge 3 [Member] Cash Flow Hedge 4 [Member] Cash Flow Hedge 4 [Member] Cash Flow Hedge 4 [Member] Derivative [Line Items] Derivative [Line Items] Settlement Date Derivative, Maturity Date Derivative, Notional Amount Derivative, Notional Amount Contractual INR/USD Foreign Exchange Rate Derivative, Forward Exchange Rate Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Schedule of Trading Securities and Other Trading Assets, Major Types of Trading Securities and Assets [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Trading Securities and Assets [Domain] Major Types of Debt and Equity Securities [Domain] Money Market Funds [Member] Money Market Funds [Member] Mutual Funds [Member] Mutual Funds [Member] An investment vehicle that is made up of a pool of funds collected from many investors for the purpose of investing in securities such as stocks, bonds, money market instruments and similar assets. Mutual funds are operated by money managers, who invest the fund's capital and attempt to produce capital gains and income for the fund's investors. Equity Securities [Member] Equity Securities [Member] Debt Securities [Member] Debt Securities [Member] U.S. treasury obligations Certificates of Deposit [Member] Certificates of Deposit [Member] Security Owned and Sold, Not yet Purchased, at Fair Value [Axis] Security Owned and Sold, Not yet Purchased, at Fair Value [Axis] Security Owned and Sold, Not yet Purchased Fair Value, Security Name [Domain] Security Owned and Sold, Not yet Purchased Fair Value, Security Name [Domain] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Securities owned — trading Trading Securities Other assets Other Assets, Fair Value Disclosure Total assets at fair value Assets, Fair Value Disclosure, Recurring Securities sold, but not yet purchased Financial Instruments Sold, Not yet Purchased, at Fair Value Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Fair Value Disclosure Total liabilities at fair value Financial and Nonfinancial Liabilities, Fair Value Disclosure Number of cash flow hedges entered into by the Company Number of cash flow hedges entered into by the Company The number of non-deliverable foreign currency contracts, which have been designated as cash flow hedges, entered into by the Company. Derivative, Cash Received on Hedge Derivative, Cash Received on Hedge Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Outstanding borrowings Schedule of Long-term Debt Instruments [Table Text Block] Fair Value, Inputs, Level 2 [Member] Long-term Debt, Gross Long-term Debt, Gross Fair value of indebtedness Debt Instrument, Fair Value Disclosure Derivative Instruments, Gain (Loss) by Income Statement Location [Axis] Income Statement Location [Axis] Income Statement and Other Comprehensive Income (Loss) Location [Domain] Income Statement Location [Domain] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Tax expense (benefit) on unrealized gain (loss) on cash flow hedges Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Tax expense on adjustment for items reclassified to earnings Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Dividends [Axis] Dividends [Axis] Dividends [Domain] Dividends [Domain] Subsequent Event [Line Items] Subsequent Event [Line Items] Dividends Payable, Date Declared Dividends Payable, Date Declared Dividends Payable, Amount Per Share Dividends Payable, Amount Per Share Dividends Payable, Date to be Paid Dividends Payable, Date to be Paid Dividends Payable, Date of Record Dividends Payable, Date of Record Earnings per Share Earnings Per Share [Text Block] Stockholders' Equity Note Disclosure [Text Block] Stockholders' Equity Note Disclosure [Text Block] Statement of Financial Position [Abstract] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] ASSETS Assets [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Cash and securities segregated under federal and other regulations Cash and Securities Segregated under Federal and Other Regulations Restricted cash Restricted Cash and Cash Equivalents Receivables from: Receivables [Abstract] Clients, net of allowance of $1,629 at September 30, 2016 and $1,464 at December 31, 2015 Receivables from Customers Product sponsors, broker-dealers, and clearing organizations Receivables from Brokers-Dealers and Clearing Organizations Advisor loans, net of allowance of $697 at September 30, 2016 and $697 at December 31, 2015 Loans Receivable, Net Others, net of allowance of $12,486 at September 30, 2016 and $9,856 at December 31, 2015 Other Receivables, Net, Current Securities owned: Securities Owned Abstract Securities owned: Trading — at fair value Held-to-maturity — at amortized cost Securities borrowed Securities Borrowed Income taxes receivable Income Taxes Receivable Fixed assets, net of accumulated depreciation and amortization of $378,764 at September 30, 2016 and $328,880 at December 31, 2015 Property, Plant and Equipment, Net Goodwill Goodwill Intangible assets, net of accumulated amortization of $371,276 at September 30, 2016 and $342,740 at December 31, 2015 Intangible Assets, Net (Excluding Goodwill) Other assets Other Assets Total assets Assets LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity [Abstract] LIABILITIES: Liabilities [Abstract] Drafts payable Drafts Payable Payables to clients Payables to Customers Payables to broker-dealers and clearing organizations Payables to Broker-Dealers and Clearing Organizations Accrued commission and advisory expenses payable Accrued Commissions And Advisory Fees Payable Balance of accrued commissions, recruiting bonus accruals, and other commissions payable. Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities Income taxes payable Taxes Payable Unearned revenue Deferred Revenue, Current Securities sold, but not yet purchased — at fair value Senior secured credit facilities, net of unamortized debt issuance cost of $23,139 at September 30, 2016 and $26,797 at December 31, 2015 Long-term Debt Leasehold Financing Obligation Leasehold Financing Obligation Leasehold Financing Obligation Deferred income taxes, net Deferred Income Tax Liabilities, Net Total liabilities Liabilities STOCKHOLDERS’ EQUITY: Equity [Abstract] STOCKHOLDERS' EQUITY: Stockholders' Equity Attributable to Parent [Abstract] Common stock, $.001 par value; 600,000,000 shares authorized; 119,766,574 shares issued at September 30, 2016 and 119,572,352 shares issued at December 31, 2015 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Treasury stock, at cost — 30,638,748 shares at September 30, 2016 and 30,048,027 shares at December 31, 2015 Treasury Stock, Value Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) Total stockholders' equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders' equity Liabilities and Equity Common Stock, Dividends, Per Share, Cash Paid Common Stock, Dividends, Per Share, Cash Paid Dividends Dividends Total cash dividends paid during the quarter Dividends, Common Stock, Cash Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Financial assets and financial liabilities measured at fair value on a recurring basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Statement of Cash Flows [Abstract] Income Statement Location [Axis] Income Statement Location [Domain] CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Adjustments to reconcile net income to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Noncash items: Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation Amortization of debt issuance costs Amortization of Debt Issuance Costs Share-based compensation Share-based Compensation Excess tax benefits related to share-based compensation Excess Tax Benefit from Share-based Compensation, Operating Activities Provision for bad debts Provision for Doubtful Accounts Deferred income tax provision Deferred Income Tax Expense (Benefit) Loan forgiveness Loan Forgiveness Forgiven portion of previously issued loans to certain shareholders, net of interest incurred. Other Other Noncash Income (Expense) Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Cash and securities segregated under federal and other regulations Increase (Decrease) in Restricted Cash and Investments for Operating Activities Deposit of restricted cash related to captive insurance subsidiary Increase in Restricted Cash Operating Activities Amount of cash outflow associated with funds that are not available for withdrawal or use (such as held in escrow) and are associated with underlying transactions that are classified as operating activities. Release of restricted cash related to captive insurance subsidiary Decrease in Restricted Cash Operating Activities Amount of cash inflow associated with funds that are not available for withdrawal or use (such as held in escrow) and are associated with underlying transactions that are classified as operating activities. Receivables from clients Increase Decrease Receivables From Clients The net change during the reporting period in receivables from brokerage clients. Brokerage client balances include margin loans to clients stated, net of allowance for doubtful accounts. Receivables from product sponsors, broker-dealers and clearing organizations Increase (Decrease) in Receivables from Brokers-Dealers and Clearing Organizations Advisor loans Increase (Decrease) in Other Loans Receivables from others Increase (Decrease) in Other Receivables Securities owned Increase (Decrease) in Trading Securities Securities borrowed Increase (Decrease) in Securities Borrowed Other assets Increase (Decrease) in Other Operating Assets Drafts payable Drafts Payable Changes In Operating Assets And Liabilities The net change during the reporting period in the amounts due on drafts payable during the reporting period. Payables to clients Increase Decrease Payables To Clients The net change during the reporting period in payables to clients, includes amounts payable on cash and margin transactions, including interest on certain client balances. Payables to broker-dealers and clearing organizations Increase (Decrease) in Payables to Broker-Dealers and Clearing Organizations Accrued commission and advisory expenses payable Changes In Accrued Commissions And Advisory Fees Payable The net change in the balance of accrued commissions, recruiting bonus accruals, and other commissions payable over the reporting period. Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Income taxes receivable/payable Increase (Decrease) in Income Taxes Unearned revenue Increase (Decrease) in Deferred Revenue Securities sold, but not yet purchased Increase (Decrease) in Financial Instruments Sold, Not yet Purchased Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Proceeds from disposal of fixed assets Proceeds from Sale of Productive Assets Purchase of securities classified as held-to-maturity Payments to Acquire Held-to-maturity Securities Proceeds from maturity of securities classified as held-to-maturity Proceeds from Sale and Maturity of Held-to-maturity Securities Deposits of restricted cash Increase in Restricted Cash Release of restricted cash Decrease in Restricted Cash Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from revolving credit facility Proceeds from Lines of Credit Repayments of revolving credit facility Repayments of Lines of Credit Repayment of senior secured term loans Repayments of Long-term Lines of Credit Tax payments related to settlement of restricted stock units Payments Related to Tax Withholding for Share-based Compensation Repurchase of common stock Payments for Repurchase of Common Stock Dividends on common stock Payments of Dividends Excess tax benefits related to share-based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Proceeds from stock option exercises and other Proceeds from Stock Options Exercised Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Period Increase (Decrease) CASH AND CASH EQUIVALENTS - Beginning of period CASH AND CASH EQUIVALENTS - End of period SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION: Supplemental Cash Flow Information [Abstract] Interest paid Interest Paid Income taxes paid Income Taxes Paid NONCASH DISCLOSURES: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Capital expenditures included in accounts payable and accrued liabilities Capital Expenditures Incurred but Not yet Paid Finance obligation related to real estate project non cash finance obligation The increase during the period in finance obligations related to real estate projects that results in no cash inflows or outflows during the period in which they occur. Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] TPG Capital [Member] TPG Capital [Member] TPG Capital Related Party Transaction [Line Items] Related Party Transaction [Line Items] Shareholder Percent Ownership in Company Shareholder Percent Ownership in Company Shareholder Percent Ownership in Company Revenue from related party transactions Revenue from Related Parties Related party transactions expenses Related Party Transaction, Expenses from Transactions with Related Party Interest Base Rate By Type [Axis] Interest Base Rate By Type [Axis] Interest base rate by type. Interest Base Rate By Type [Domain] Interest Base Rate By Type [Domain] Interest base rate by type. Base Rate [Member] Base Rate [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Alternative Base Rate [Member] Alternative Base Rate [Member] Alternative Base Rate Extended Term Loan B [Member] Extended Term Loan B [Member] Extended Term Loan B of Credit Agreement entered into on November 20, 2015 [Member] New Term Loan B [Member] New Term Loan B [Member] New Term Loan B of Credit Agreement entered into on November 20, 2015 [Member] Debt Instrument, Basis Spread on Variable Rate Benchmark Short-Term Interest Rate Benchmark Short-Term Interest Rate Benchmark Short-Term Interest Rate Long-term Debt, Current and Noncurrent [Abstract] Long-term Debt, Current and Noncurrent [Abstract] Balance Less current portion Long-term Debt, Current Maturities Interest Rate Debt Instrument, Interest Rate, Effective Percentage Net capital and net capital requirements for the Company's broker-dealer subsidiaries Regulatory Capital Requirements [Abstract] Net Capital Net Capital Minimum Net Capital Required for Broker-Dealer Subsidiary Minimum Net Capital Required for Broker-Dealer Subsidiary Income Taxes Income Tax Disclosure [Text Block] Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] NET INCOME Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Unrealized gain (loss) on cash flow hedges, net of tax expense (benefit) of $85, ($98), $133, and $96 for the three and nine months ended September 30, 2016 and 2015, respectively Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Reclassification adjustment for realized gain on cash flow hedges included in professional services in the condensed consolidated statements of income, net of tax expense of $48, $62, $204, and $290 for the three and nine months ended September 30, 2016 and 2015, respectively Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Total other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax TOTAL COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Parent Subsequent Event [Abstract] Subsequent Event [Abstract] Subsequent Events [Text Block] Subsequent Events [Text Block] Portion of Design and Construction Costs Company is Obligated to Pay Portion of Design and Construction Costs Company is Obligated to Pay Portion of Design and Construction Costs Company is Obligated to Pay Other Commitment Other Commitment Lessee Leasing Arrangements, Operating Leases, Term of Contract Lessee Leasing Arrangements, Operating Leases, Term of Contract Collateral Securities Repledged, Delivered, or Used Collateral Securities Repledged, Delivered, or Used Collateral security Customer Securities for which Entity has Right to Sell or Repledge, Fair Value Amount pledged with client-owned securities Customer Securities for which Entity has Right to Sell or Repledge, Fair Value of Securities Sold or Repledged Remaining collateral securities that can be re-pledged, loaned, or sold Fair Value of Securities Received as Collateral that Can be Resold or Repledged Security Owned and Pledged as Collateral, Fair Value [Abstract] Security Owned and Pledged as Collateral, Fair Value [Abstract] Trading securities pledged to clearing organizations Security Owned and Pledged as Collateral, Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Expected life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected stock price volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Fair value of options Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other Assets [Member] Other Assets [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Fair value of cash flow hedges Foreign Currency Cash Flow Hedge Derivative at Fair Value, Net Loss Contingencies [Table] Loss Contingencies [Table] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Litigation Status [Axis] Litigation Status [Axis] Litigation Status [Domain] Litigation Status [Domain] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Loss Contingency, Range of Possible Loss, Portion Not Accrued Loss Contingency, Range of Possible Loss, Portion Not Accrued Basic weighted-average number of shares outstanding Dilutive common share equivalents Weighted Average Number Diluted Shares Outstanding Adjustment Diluted weighted-average number of shares outstanding Basic earnings per share Diluted earnings per share Organization and Description of the Company Nature of Operations [Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Number of Shares Outstanding, Beginning Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Number of Shares, Granted Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Number of Shares, Exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Number of Shares, Forfeited Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Number of Shares Outstanding, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number Number of Shares Exercisable, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Weighted-Average Exercise Price, Granted Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Weighted-Average Exercise Price, Exercised Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Weighted-Average Exercise Price, Forfeited Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Weighted-Average Exercise Price, Outstanding, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Weighted-Average Exercise Price, Exercisable, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Weighted-Average Remaining Contractual Term, Options Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Weighted-Average Remaining Contractual Term, Options Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Aggregate Intrinsic Value, Outstanding, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate Intrinsic Value, Outstanding, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Statement of Stockholders' Equity [Abstract] Common Stock Common Stock [Member] Additional Paid-In Capital Additional Paid-in Capital [Member] Treasury Stock Treasury Stock [Member] Accumulated Other Comprehensive Income (Loss) Retained Earnings Retained Earnings [Member] BEGINNING BALANCE BEGINNING BALANCE, shares Shares, Issued Net income and other comprehensive income (loss), net of tax expense Issuance of common stock to settle restricted stock units, net Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Issuance of common stock to settle restricted stock units, net, shares Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Treasury stock purchases Treasury stock purchases, shares Cash dividends on common stock Stock option exercises and other (in shares) Stock option exercises and other Stock Issued During Period, Value, Stock Options Exercised Share-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Excess tax benefits (tax deficiency) from share-based compensation Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net ENDING BALANCE ENDING BALANCE, shares Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block]