Other Assets and Liabilities - Summary of Components of Other Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Past Due [Line Items]
Debt securities held-to-maturity	$ 77,597	$ 77,445
CECL reserve	(889)	(1,723)	$ (5,122)	$ 0
Debt securities held-to-maturity, net	76,708	75,722
Accrued interest receivable	67,472	66,757
Derivative assets	31,789	522
Loan portfolio payments held by servicer	8,916	73,224
Prepaid expenses	778	973
Collateral deposited under derivative agreements	0	51,050
Prepaid taxes	0	376
Other	919	1,195
Total	$ 186,582	$ 269,819