Debt Securities Available for Sale - Expected Maturities of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
One year or less	$ 35,265
More than one year to five years	87,687
More than five years to ten years	68,715
Available-for-sale debt securities, allocated and single maturity date, total	191,667
Mortgage-backed securities and collateralized mortgage obligations	1,026,493
Amortized Cost	1,218,160	$ 1,515,941
Fair Value
One year or less	35,218
More than one year to five years	84,301
More than five years to ten years	54,600
Available-for-sale debt securities, allocated and single maturity date, total	174,119
Mortgage-backed securities and collateralized mortgage obligations	844,260
Fair Value	$ 1,018,379	$ 1,328,634

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