Qualified Affordable Housing Projects and Other Tax Credit Investments - Schedule of Qualified Affordable Housing Projects and Other Tax Credit Investments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Investment Holdings [Line Items]
Investment	$ 61,820		$ 59,661
Unfunded Commitment	30,472		25,926
Amortization Expense	6,291	$ 1,052
Tax Expense (Benefit) Recognized	(2,775)	(1,286)
LIHTC
Investment Holdings [Line Items]
Investment, Proportional amortization	28,909		29,735
Unfunded Commitment, Proportional amortization	3,907		3,911
Amortization Expense	776	792
Tax Expense (Benefit) Recognized	(1,019)	(1,042)
FHTC
Investment Holdings [Line Items]
Investment, Equity	25,760		22,403
Unfunded Commitment, Equity	22,896		17,886
Amortization Expense	5,143
Tax Expense (Benefit) Recognized	(1,356)
Renewable Energy
Investment Holdings [Line Items]
Investment, Equity	7,151		7,523
Unfunded Commitment, Equity	3,669		$ 4,129
Amortization Expense	372	260
Tax Expense (Benefit) Recognized	$ (400)	$ (244)