Other Assets and Liabilities - Summary of Components of Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Debt securities held-to-maturity	$ 86,638	$ 96,167
Accrued interest receivable	66,649	56,679
Loan portfolio payments held by servicer	49,584	6,133
Collateral deposited under derivative agreements	30,800
Derivative assets	1,079	9,916
Prepaid expenses	739	647
Prepaid taxes	376	6
Other	1,115	965
Total	$ 236,980	$ 170,513