Investments - Summary of Investments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) investment	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Schedule of Investments
Cost method investment ownership percentage	10.00%
Number of equity method investments | investment	8
Fair Value, Investments, Privately Held Entities that Calculate NAV, Unfunded Commitments	$ 378,700
Limited partnership maximum expiration terms	12 years
Weighted-average remaining liquidation term (in years)	5 years 3 months 18 days
Limited partnership liquidation, expected initial term (in years)	10 years
Investments in privately held entities that do not report NAV, cumulative downward price adjustment	$ (1,600)
Investments in privately held entities that do not report NAV, cumulative impairment loss	(68,300)
Income from equity method investments	194	$ 220
Summary of Investment [Abstract]
Investment at fair value, cost	1,173,749		$ 1,152,613
Cumulative unrealized gains on investments	459,271		506,404
Cumulative unrealized losses on investments	(122,518)		(109,402)
Investments accounted for under the equity method	62,516		65,459
Total investments held at adjusted carrying value or fair value	1,573,018		1,615,074
Investment Income, Net [Abstract]
Realized gains	20,744	23,114
Unrealized losses	(65,855)	(263,433)
Investment loss	(45,111)	(240,319)
Equity Method Investments
Schedule of Investments
Income from equity method investments	(6,200)
Investments in publicly traded companies
Summary of Investment [Abstract]
Investment at fair value, cost	200,833		210,986
Cumulative unrealized gains on investments	63,308		96,271
Cumulative unrealized losses on investments	(110,800)		(100,118)
Investments at fair value, book value	$ 153,341		207,139
Investments in privately held entities that report NAV
Schedule of Investments
Weighted-average remaining liquidation term (in years)	8 years 6 months
Summary of Investment [Abstract]
Investment at fair value, cost	$ 469,863		452,391
Cumulative unrealized gains on investments	299,235		315,071
Cumulative unrealized losses on investments	(10,144)		(7,710)
Investments at fair value, book value	758,954		759,752
Investments in privately held entities that do not report NAV | Entities with observable price change
Schedule of Investments
Investment in privately held entities that do not report NAV, cumulative price adjustments	26,900
Investments in privately held entities that do not report NAV, cumulative upward price adjustment	96,700
Annual adjustments recognized on investments in privately held entities that do not report NAV	510	642
Investments in privately held entities that do not report NAV, annual upward price adjustment	1,800	6,800
Investments in privately held entities that do not report NAV, annual downward price adjustment	2,300	6,200
Summary of Investment [Abstract]
Investment at fair value, cost	101,703		100,296
Cumulative unrealized gains on investments	96,728		95,062
Cumulative unrealized losses on investments	(1,574)		(1,574)
Investments in privately held entities that do not report fair value, book value	196,857		193,784
Investments in privately held entities that do not report NAV | Entities without observable price changes
Summary of Investment [Abstract]
Investment at fair value, cost	401,350		388,940
Cumulative unrealized gains on investments	0		0
Cumulative unrealized losses on investments	0		0
Investments in privately held entities that do not report fair value, book value	401,350		$ 388,940
Total investments held
Investment Income, Net [Abstract]
Unrealized losses	$ (38,300)	$ (224,400)