| Cover Page - USD ($) $ in Millions | 12 Months Ended | ||
| Mar. 31, 2021 | May 26, 2021 | Sep. 30, 2020 | |
| Document Type | 10-K/A | ||
| Document Annual Report | true | ||
| Document Period End Date | Mar. 31, 2021 | ||
| Current Fiscal Year End Date | --03-31 | ||
| Document Transition Report | false | ||
| Entity File Number | 001-38021 | ||
| Entity Registrant Name | HAMILTON LANE INCORPORATED | ||
| Entity Incorporation, State or Country Code | DE | ||
| Entity Tax Identification Number | 26-2482738 | ||
| Entity Address, Address Line One | 110 Washington Street, | ||
| Entity Address, Address Line Two | Suite 1300 | ||
| Entity Address, City or Town | Conshohocken, | ||
| Entity Address, State or Province | PA | ||
| Entity Address, Postal Zip Code | 19428 | ||
| City Area Code | 610 | ||
| Local Phone Number | 934-2222 | ||
| Title of 12(b) Security | Class A Common Stock, $0.001 par value per share | ||
| Trading Symbol | HLNE | ||
| Security Exchange Name | NASDAQ | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| Entity Current Reporting Status | Yes | ||
| Entity Interactive Data Current | Yes | ||
| Entity Filer Category | Large Accelerated Filer | ||
| Entity Emerging Growth Company | false | ||
| Entity Small Business | false | ||
| ICFR Auditor Attestation Flag | true | ||
| Entity Shell Company | false | ||
| Entity Public Float | $ 1,980.4 | ||
| Documents Incorporated by Reference | Part III of this Form 10-K incorporates by reference information from the registrant’s definitive proxy statement related to the 2021 annual meeting of stockholders. | ||
| Amendment Description | The Company is filing this Amendment to: (i) amend Item 9B of Part II to disclose information regarding compensatory awards to certain of the Company’s named executive officers that was required to be disclosed on a Current Report on Form 8-K during the fourth quarter of the fiscal year covered by this Annual Report on Form 10-K, but which was not timely reported on a Form 8-K during that period; (ii) amend the Exhibit Index referenced in Item 15 of Part IV to add related Exhibits 10.32, 10.33 and 10.34; and (iii) update the Company’s well-known seasoned issuer status as a result of the foregoing. This Amendment also contains currently dated certifications under the Sarbanes-Oxley Act of 2002, filed as exhibits 31.3, 31.4 and 32. | ||
| Entity Central Index Key | 0001433642 | ||
| Amendment Flag | true | ||
| Document Fiscal Year Focus | 2021 | ||
| Document Fiscal Period Focus | FY | ||
| Common Class A | |||
| Entity Common Stock, Shares Outstanding | 36,290,183 | ||
| Common Class B | |||
| Entity Common Stock, Shares Outstanding | 16,739,846 |
