Other Assets and Liabilities - Summary of Components of Other Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Past Due [Line Items]
Debt securities held-to-maturity	$ 82,058	$ 86,638
CECL reserve	112,694	112,694
Debt securities held-to-maturity, net	76,936	86,638
Accrued interest receivable	72,578	66,649
Loan portfolio payments held by servicer	656	49,584
Prepaid expenses	616	739
Prepaid taxes	376	376
Derivative assets	1	1,079
Collateral deposited under derivative agreements		30,800
Other	994	1,115
Total	152,157	$ 236,980
Held To Maturity Debt Securities [Member]
Debt Securities, Held-to-maturity, Past Due [Line Items]
CECL reserve	$ (5,122)