Loans Held-for-Investment, Net of Allowance for Credit Losses - Roll Forward of Loans Held-for-Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Loans Held-for-Investment [Roll Forward]
Balance at beginning of period	$ 3,847,803	$ 4,226,212
Originations, additional fundings, upsizing of loans and capitalized deferred interest	834,461	372,859
Repayments	(960,330)	(486,422)
Transfer of Portfolio Loans and Leases to Held-for-sale	0	(210,452)	$ 0
Net discount accretion (premium amortization)	5	13
Increase in net deferred origination fees	(9,766)	(3,642)
Amortization of net deferred origination fees	13,106	15,901
Benefit from (provision for) credit losses	16,029	(66,666)
Balance at end of period	$ 3,741,308	$ 3,847,803	$ 4,226,212