Investment Securities Contractual Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Due after five years through ten years, amortized cost	$ 46,878
Due after ten years, amortized cost	241,743
Subtotal before securities without single maturities, amortized cost	288,621
Collateralized mortgage obligations and mortgage-backed securities, amortized cost	477,276
Securities available for sale, at amortized cost	765,897	$ 412,559
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Due after five years through ten years, fair value	46,938
Due after ten years, fair value	240,639
Subtotal before securities without single maturities, fair value	287,577
Collateralized mortgage obligations and mortgage-backed securities, fair value	475,820
Investment securities available for sale, fair value	$ 763,397	$ 420,571

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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