Investments - Narrative (Details)		3 Months Ended	12 Months Ended
	Sep. 25, 2017 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2021 USD ($) investment	Dec. 31, 2020 USD ($) investment	Dec. 31, 2019 USD ($)
Unusual or Infrequent Item, or Both [Line Items]
Non-cash exchange of available-for-sale debt securities		$ 18,300,000
Loss on investments, net		$ 4,400,000
Impairment loss on equity securities without readily determinable fair value			$ 16,677,000	$ 19,605,000
Proceeds from sale of equity securities without readily determinable fair value			14,300,000
Realized loss on securities			300,000
Equity securities, cumulative impairment loss			$ 40,500,000	23,800,000
Number of investments in an unrealized loss position | investment			0
Other-than-temporary impairment losses recognized on debt securities			$ 0	0	$ 0
Variable interest entity, amount committed to invest	$ 200,000,000
Variable interest entity, ownership percentage	76.60%
Annual management fee percentage	2.00%
Management fee annual reduction percentage	10.00%
Entitled carried interest percentage	20.00%
Fund investment period	6 years
Variable interest entity, amount of capital call notices received			22,200,000	32,900,000
Variable interest entity, amount paid			22,200,000	31,900,000
Distribution from equity method investment			15,327,000	0	10,288,000
Net investment income (loss)			35,845,000	(11,338,000)	(168,000)
Management fees recognized			$ 3,000,000	3,000,000	$ 3,000,000
COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Net investment income (loss)				$ (4,300,000)
Number of investments impaired | investment				2
Equity method investment, impairment				$ 7,000,000