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Intangibles and Goodwill - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 20, 2021	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 1,900,000	$ 800,000	$ 2,500,000	$ 1,700,000
Finite-Lived Intangible Assets [Line Items]
Goodwill	582,973,000		582,973,000			$ 6,792,000
Goodwill, impairment loss	$ 0		$ 0			$ 0
Greenspring
Finite-Lived Intangible Assets [Line Items]
Goodwill					$ 576,181,000
Management contracts \| Greenspring
Finite-Lived Intangible Assets [Line Items]
Business acquisition, finite-lived intangible assets					310,900,000
Client relationships \| Greenspring
Finite-Lived Intangible Assets [Line Items]
Business acquisition, finite-lived intangible assets					96,650,000
Service agreements \| Greenspring
Finite-Lived Intangible Assets [Line Items]
Business acquisition, finite-lived intangible assets					$ 9,500,000