Goodwill and Other Intangible Assets - Total Amortizing Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 138,421	$ 138,421
Accumulated Amortization	134,423	124,256
Net Carrying Amount	3,998	14,165
Core Deposit [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	131,664	131,664
Accumulated Amortization	127,746	119,125
Net Carrying Amount	3,918	12,539
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,757	6,757
Accumulated Amortization	6,677	5,131
Net Carrying Amount	$ 80	$ 1,626