Qualified Affordable Housing Projects and Other Tax Credit Investments - Schedule of Qualified Affordable Housing Projects and Other Tax Credit Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Total	$ 59,661	$ 54,404
Total	25,926	38,548
Amortization Expense	5,917	25,534	$ 13,655
Tax Expense (Benefit) Recognized	(7,086)	(29,377)	(15,701)
LIHTC [Member]
Investment Holdings [Line Items]
Proportional amortization method of investment	29,735	28,396
Unfunded commitment, Proportional amortization	3,911	2,238
Amortization Expense	3,168	2,585	1,922
Tax Expense (Benefit) Recognized	(4,102)	(3,349)	(2,666)
FHTC [Member]
Investment Holdings [Line Items]
Equity method investment	22,403	16,815
Unfunded commitment, Equity	17,886	17,945
Amortization Expense	1,113	9,206	10,441
Tax Expense (Benefit) Recognized	(1,244)	(10,775)	(11,348)
CReED [Member]
Investment Holdings [Line Items]
Equity method investment		17
Unfunded commitment, Equity		538
Amortization Expense	13	687	800
Tax Expense (Benefit) Recognized		(687)	(1,074)
Renewable Energy [Member]
Investment Holdings [Line Items]
Equity method investment	7,523	9,176
Unfunded commitment, Equity	4,129	17,827
Amortization Expense	1,623	13,056	492
Tax Expense (Benefit) Recognized	$ (1,740)	$ (14,566)	$ (613)