Document and Entity Information
| Document and Entity Information Document | Apr. 30, 2020 |
| Cover page. [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Apr. 30, 2020 |
| Entity Registrant Name | LPL Financial Holdings Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-34963 |
| Entity Tax Identification Number | 20-3717839 |
| Entity Address, Address Line One | 75 State Street |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02109 |
| City Area Code | (617) |
| Local Phone Number | 423-3644 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock - par value $0.001 per share |
| Trading Symbol | LPLA |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001397911 |
| Amendment Flag | false |