Fair Value of Assets and Liabilities - Schedule of Assets Recorded at Fair Value on a Non-Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights, fair value	$ 15,362		$ 7,515
Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains (losses) on assets held, mortgage servicing rights	421
Gains (Losses) on assets held	421
Fair Value, Nonrecurring | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights, fair value	14,744	$ 12,377
Assets, Fair Value Disclosure	14,744	12,377
Fair Value, Nonrecurring | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Collateral dependent impaired loans	7,462	6,318
Fair value, Foreclosed real estate	132	132
Assets, Fair Value Disclosure	$ 7,594	$ 6,450