Fair Value of Financial Instruments - Additional Information about Level 3 Assets Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 192,217	$ 161,172
Total Net Gains Included in Net Income	219,827	14,606
Purchases	0	0
Sales/Exits	(181,413)	(30,039)
Issuances	6,565	4,519
Other	(39)	0
Transfers Out of Level 3	(3,775)	(266)
Ending Balance	233,382	149,992
Equity warrant assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	192,217	161,038
Total Net Gains Included in Net Income	219,827	14,601
Purchases	0	0
Sales/Exits	(181,413)	(30,034)
Issuances	6,565	4,519
Other	(39)	0
Transfers Out of Level 3	(3,775)	(266)
Ending Balance	$ 233,382	149,858
Non-marketable securities | Unconsolidated venture capital and private equity fund investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		134
Total Net Gains Included in Net Income		5
Purchases		0
Sales/Exits		(5)
Issuances		0
Other		0
Transfers Out of Level 3		0
Ending Balance		$ 134