Investment Securities - Maturity of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands		Dec. 31, 2025	Dec. 31, 2024
Investment Securities [Line Items]
Due within 1 year, Amortized Cost		$ 1,000
Due after 1 but within 5 years, Amortized Cost		35,035
Due after 5 but within 10 years, Amortized Cost		19,494
Due after 10 years, Amortized Cost		0
Debt securities gross, Amortized Cost		55,529
Total debt securities, Amortized Cost		1,096,232	$ 1,267,747
Due within 1 year, Estimated Fair Value		984
Due after 1 but within 5 years, Estimated Fair Value		34,797
Due after 5 but within 10 years, Estimated Fair Value		18,705
Due after 10 years, Estimated Fair Value		0
Debt securities gross, Estimated Fair Value		54,486
Debt Securities, Available-for-Sale		1,014,194	$ 1,147,623
Mortgage-Backed Securities [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	[1]	1,040,703
Debt Securities, Available-for-Sale	[1]	959,708
US Government Agencies Debt Securities [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	[1]	704,200
Debt Securities, Available-for-Sale	[1]	664,200
Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	[1]	336,500
Debt Securities, Available-for-Sale		$ 295,500

[1] Mortgage-Backed Securities include an amortized cost of $704.2 million and a fair value of $664.2 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $336.5 million and a fair value of $295.5 million for Obligations of U.S. Government-sponsored enterprises issued by Fannie Mae and Freddie Mac.