Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income	General Partnerships Noncontrolling Interests	Hamilton Lane Advisors, L.L.C. Noncontrolling Interests
Beginning balance at Mar. 31, 2018	$ 136,074	$ 22	$ 26	$ 73,829	$ 4,549	$ 0	$ 7,266	$ 50,382
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	55,675				20,067		394	35,214
Other comprehensive loss	0
Equity-based compensation	3,220			1,369				1,851
Issuance of shares for contingent compensation payout	0
Repurchase of Class A shares for employee tax withholding	(174)			(73)				(101)
Deferred tax adjustment	6,170			6,170
Dividends declared	(9,458)				(9,458)
Capital contributions from (distributions to) non-controlling interests, net	(787)						(787)
Member distributions	(29,568)							(29,568)
Secondary offering	(2)	3	(2)	5,891				(5,894)
Equity reallocation between controlling and non-controlling interests	0			(1,508)				1,508
Ending balance at Sep. 30, 2018	162,147	25	24	86,089	15,178	0	6,873	53,958
Beginning balance at Jun. 30, 2018	144,925	22	26	74,802	8,685	0	6,709	54,681
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	32,572				11,222		514	20,836
Other comprehensive loss	0
Equity-based compensation	1,610			691				919
Repurchase of Class A shares for employee tax withholding	(24)			(10)				(14)
Deferred tax adjustment	6,170			6,170
Dividends declared	(4,729)				(4,729)
Capital contributions from (distributions to) non-controlling interests, net	(350)						(350)
Member distributions	(18,025)							(18,025)
Secondary offering	(2)	3	(2)	5,891				(5,894)
Equity reallocation between controlling and non-controlling interests	0			(1,455)				1,455
Ending balance at Sep. 30, 2018	162,147	25	24	86,089	15,178	0	6,873	53,958
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment from adoption of accounting guidance	997
Beginning balance at Mar. 31, 2019	169,722	27	24	92,482	17,686	7	5,716	53,780
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	59,726				26,680		549	32,497
Other comprehensive loss	(29)					(14)		(15)
Equity-based compensation	3,502			1,777				1,725
Issuance of shares for contingent compensation payout	425			214				211
Repurchase of Class A shares for employee tax withholding	(45)			(23)				(22)
Deferred tax adjustment	6,211			6,211
Dividends declared	(15,368)				(15,368)
Capital contributions from (distributions to) non-controlling interests, net	(673)						(673)
Member distributions	(19,430)							(19,430)
Secondary offering	(2)	3	(2)	6,367				(6,370)
Employee Share Purchase Plan share issuance	592			301				291
Equity reallocation between controlling and non-controlling interests	0			389				(389)
Ending balance at Sep. 30, 2019	204,631	30	22	107,718	28,998	(7)	5,592	62,278
Beginning balance at Jun. 30, 2019	177,835	27	24	93,543	21,722	14	5,932	56,573
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	32,273				15,299		45	16,929
Other comprehensive loss	(42)					(21)		(21)
Equity-based compensation	1,761			902				859
Repurchase of Class A shares for employee tax withholding	(28)			(14)				(14)
Deferred tax adjustment	6,207			6,207
Dividends declared	(8,023)				(8,023)
Capital contributions from (distributions to) non-controlling interests, net	(385)						(385)
Member distributions	(5,281)							(5,281)
Secondary offering	(2)	3	(2)	6,367				(6,370)
Employee Share Purchase Plan share issuance	316			162				154
Equity reallocation between controlling and non-controlling interests	0			551				(551)
Ending balance at Sep. 30, 2019	204,631	$ 30	$ 22	$ 107,718	$ 28,998	$ (7)	$ 5,592	$ 62,278
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment from adoption of accounting guidance	$ 0