Low Income Housing Tax Credits and Other Tax Credit Investments - Summary of the Company's Investments in Low Income Housing Projects Accounted for Using the Proportional Amortization Method (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Investments in Affordable Housing Projects [Abstract]
Current recorded investment included in other assets	$ 82,533		$ 82,533		$ 58,504
Commitments to fund qualified affordable housing projects included in recorded investment noted above	49,611		49,611		$ 31,487
Tax credits and benefits recognized	1,730	$ 1,539	4,717	$ 4,597
Amortization expense included in income tax expense	$ 1,496	$ 1,263	$ 4,255	$ 3,715