Other Assets and Liabilities - Summary of Components of Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Past Due [Line Items]
Debt securities held-to-maturity	$ 77,445	$ 86,638
CECL reserve	(1,723)	0
Debt securities held-to-maturity, net	75,722	86,638
Loan portfolio payments held by servicer	73,224	49,584
Accrued interest receivable	66,757	66,649
Collateral deposited under derivative agreements	51,050	30,800
Prepaid expenses	973	739
Derivative assets	522	1,079
Prepaid taxes	376	376
Other	1,195	1,115
Total	$ 269,819	$ 236,980