Investment Information - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) lots	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) lots
Continuous unrealized loss, qualitative disclosures:
Number of positions in an unrealized loss position (lots) | lots	6,550		4,700
Total number of positions (lots) | lots	9,060		10,240
Largest single loss	$ 3,600		$ 1,100
Narrative items:
Equity securities, at fair value	1,002,572		$ 1,804,170
Equity in net (loss) income of investment funds accounted for using the equity method	$ 36,305	$ 71,686
Time lag for reporting	3 months
Minimum
Narrative items:
Time lag for reporting	1 month
Maximum
Narrative items:
Time lag for reporting	3 months