Investment Information - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) lots	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) lots	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) lots
Continuous unrealized loss, qualitative disclosures:
Number of positions in an unrealized loss position (lots) | lots	8,360		8,360		4,700
Total number of positions (lots) | lots	10,440		10,440		10,240
Largest single loss	$ 5,700		$ 5,700		$ 1,100
Narrative items:
Equity securities, at fair value	772,689		772,689		$ 1,804,170
Equity in net (loss) income of investment funds accounted for using the equity method	$ 58,061	$ 122,186	$ 94,366	$ 193,872
Time lag for reporting			3 months
Minimum
Narrative items:
Time lag for reporting			1 month
Maximum
Narrative items:
Time lag for reporting			3 months