Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities Available for Sale, Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Investment Securities [Line Items]
Amortized Cost	$ 1,045,579	$ 805,515
Securities available for sale	1,041,380	$ 831,223
US Government Agencies Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	370,300
Securities available for sale	368,000
Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Amortized Cost	632,700
Securities available for sale	$ 630,000