Fair Values of Assets and Liabilities (Summary of Assets Measured at Fair Value on a Nonrecurring Basis) (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022	Jun. 30, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	$ 85,557	$ 85,557	$ 113,854
Fair value losses - individually assessed loans - foreclosure probable and collateral-dependent	9,161	12,041
Fair value losses - other real estate owned	282	282
Fair value losses	9,443	12,323
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	85,600	85,600
Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	59,921	59,921
Other real estate owned	6,839	6,839
Total	66,760	66,760
Measured at fair value on a non-recurring basis: | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	0	0
Other real estate owned	0	0
Total	0	0
Measured at fair value on a non-recurring basis: | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	0	0
Other real estate owned	0	0
Total	0	0
Measured at fair value on a non-recurring basis: | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	59,921	59,921
Other real estate owned	6,839	6,839
Total	$ 66,760	$ 66,760