Securities - Contractual Maturities of Debt Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Amortized Cost
Due in one year or less	$ 35,066
Due after one year through five years	87,794
Due after five years through ten years	95,316
Due after ten years	21,022
Available-for-Sale Debt Securities With Maturities, Amortized Cost	239,198
Amortized Cost	815,280	$ 737,005
Fair Value
Due in one year or less	35,402
Due after one year through five years	91,953
Due after five years through ten years	97,577
Due after ten years	23,336
Available-for-Sale Debt Securities With Maturities, Fair Value	248,268
Total Available-for-Sale Debt Securities, Fair Value	839,279	770,393
Collateralized mortgage obligations of U.S. government corporations and agencies
Amortized Cost
Available-for-Sale Debt Securities With Maturities	197,458
Amortized Cost	197,458	202,975
Fair Value
Available-for-Sale Debt Securities With Maturities	201,350
Total Available-for-Sale Debt Securities, Fair Value	201,350	209,296
Residential mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Available-for-Sale Debt Securities With Maturities	63,896
Amortized Cost	63,896	66,960
Fair Value
Available-for-Sale Debt Securities With Maturities	63,859
Total Available-for-Sale Debt Securities, Fair Value	63,859	67,778
Commercial mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Available-for-Sale Debt Securities With Maturities	314,228
Amortized Cost	314,228	258,875
Fair Value
Available-for-Sale Debt Securities With Maturities	325,303
Total Available-for-Sale Debt Securities, Fair Value	325,303	$ 273,681
Corporate obligations
Amortized Cost
Available-for-Sale Debt Securities With Maturities	500
Fair Value
Available-for-Sale Debt Securities With Maturities	$ 499