Loans and Allowance for Loan Losses - Summary of Non Accrual Loan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	[1]
Receivables [Abstract]
Total nonaccrual loans	$ 26,484	$ 34,877	$ 98,494
Interest foregone for the year	2,152	1,153	823
Amount of foregone interest applied to principal for the year	254	535	52
Interest foregone life-to-date	2,744	1,952	12,485
Amount of foregone interest applied to principal life-to-date	$ 471	$ 1,214	$ 3,495
Percentage of nonaccrual loans to gross loan portfolio	2.00%	3.00%	31.00%

[1] Does not include the Bank’s nonaccrual loans of $32,668, interest income foregone for the year of $795 and foregone interest paid and applied to principal for the year of $917, interest income foregone life-to-date of $1,487 and foregone interest paid and applied to principal life-to-date of $1,221.