Document and Entity Information
6 Months Ended
Jun. 30, 2011
Jul. 26, 2011
Document and Entity Information [Abstract]    
Entity Registrant Name LPL Investment Holdings Inc.  
Entity Central Index Key 0001397911  
Document Type 10-Q  
Document Period End Date Jun. 30, 2011  
Amendment Flag false  
Document Fiscal Year Focus 2011  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --12-31  
Entity Well-known Seasoned Issuer Yes  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   107,828,819