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Investment Securities - Maturity of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands		Dec. 31, 2023	Dec. 31, 2022
Investment Securities [Line Items]
Due within 1 year, Amortized Cost		$ 6,255
Due after 1 but within 5 years, Amortized Cost		9,796
Due after 5 but within 10 years, Amortized Cost		46,061
Due after 10 years, Amortized Cost		0
Debt securities gross, Amortized Cost		62,112
Total debt securities, Amortized Cost		1,138,425	$ 898,702
Due within 1 year, Estimated Fair Value		6,246
Due after 1 but within 5 years, Estimated Fair Value		9,654
Due after 5 but within 10 years, Estimated Fair Value		41,629
Due after 10 years, Estimated Fair Value		0
Debt securities gross, Estimated Fair Value		57,529
Debt Securities, Available-for-Sale		1,020,986	$ 762,661
Mortgage-Backed Securities [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	[1]	1,076,313
Debt Securities, Available-for-Sale	[1]	963,457
US Government Agencies Debt Securities [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost		516,500
Debt Securities, Available-for-Sale		468,900
Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost		559,800
Debt Securities, Available-for-Sale		$ 494,600
[1] Mortgage Backed Securities include an amortized cost of $516.5 million and a fair value of $468.9 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $559.8 million and a fair value of $494.6 million for Obligations of U.S. Government-sponsored enterprises issued by Fannie Mae and Freddie Mac.

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