Summary of Significant Accounting Policies - Change in Unrealized Gains or Losses Within Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in Unrealized Gains or Losses Within Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ (2,696,741)	$ (1,122,721)	$ (539,198)
Adjustment for the adoption of ASU 2016-01	0	0	(981)
Ending balance	1,238,039	(2,696,741)	(1,122,721)
Accumulated Other Comprehensive Income
Change in Unrealized Gains or Losses Within Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	411	139	1,141
Add: Unrealized (losses) gains on available-for-sale debt securities	(1,152)	405	0
Adjustment for the adoption of ASU 2016-01	0	0	(981)
Less: Reclassification of unrealized gains to interest and other income, net, in the consolidated statements of operations	(6)	(133)	(21)
Net impact to other comprehensive (loss) income in current period	(1,158)	272	(1,002)
Ending balance	$ (747)	$ 411	$ 139