Fair Value Measurements - Activity for Level 3 Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Level 3 CMO [Roll Forward]
Unrealized net holding gains (losses) on securities available-for-sale arising during the period	$ (609,826,000)	$ (91,523,000)
Discounted Cash Flow
Level 3 CMO [Roll Forward]
Financing Receivable, before Allowance for Credit Loss, Average Yield	6.82%
Level 3
Level 3 CMO [Roll Forward]
Equity warrants, Balance, beginning of period	$ 3,555,000
Total included in earnings, Equity Warrants	629,000
Total included in other comprehensive income	0
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants	178,000
Sales, Equity Warrants	(584,000)
Net settlements, Equity Warrants	0
Fair Value, Equity, Transfers to Level 1, Amount	(7,000)
Fair Value, Measurements, Recurring
Level 3 CMO [Roll Forward]
Equity warrants, Balance, beginning of period	3,555,000
Equity warrants, Balance, end of period	3,771,000
Fair Value, Measurements, Recurring | Level 3
Level 3 CMO [Roll Forward]
Equity warrants, Balance, beginning of period	3,555,000
Equity warrants, Balance, end of period	3,771,000
Asset-backed | Fair Value, Measurements, Recurring | Level 3
Level 3 CMO [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	15,001,000
Total included in earnings	(4,000)
Total included in other comprehensive income	(94,000)
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants	0
Net settlements	(9,327,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	5,576,000
Unrealized net holding gains (losses) on securities available-for-sale arising during the period	(53,000)
Fair Value, Equity, Transfers to Level 1, Amount	0
Warrant
Level 3 CMO [Roll Forward]
Fair value transfers of assets measured on a recurring basis	$ 7,000