Securities - Amortized Cost and Fair Value of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Amortized Cost
Due in one year or less	$ 40,495
Due after one year through five years	103,119
Due after five years through ten years	41,370
Due after ten years	21,190
Debt Securities Available-for-Sale With Maturities	206,174
Total Debt Securities Available-for-Sale, Amortized Cost	737,005	$ 768,427
Fair Value
Due in one year or less	41,006
Due after one year through five years	109,043
Due after five years through ten years	43,765
Due after ten years	23,799
Debt Securities Available-for-Sale With Maturities	217,613
Total Debt Securities Available-for-Sale	770,393	779,133
Collateralized mortgage obligations of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	202,975
Total Debt Securities Available-for-Sale, Amortized Cost	202,975	186,879
Fair Value
Debt Securities Available-for-Sale With Maturities	209,296
Total Debt Securities Available-for-Sale	209,296	189,348
Residential mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	66,960
Total Debt Securities Available-for-Sale, Amortized Cost	66,960	22,120
Fair Value
Debt Securities Available-for-Sale With Maturities	67,778
Total Debt Securities Available-for-Sale	67,778	22,418
Commercial mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	258,875
Total Debt Securities Available-for-Sale, Amortized Cost	258,875	273,771
Fair Value
Debt Securities Available-for-Sale With Maturities	273,681
Total Debt Securities Available-for-Sale	273,681	275,870
Corporate Obligations
Amortized Cost
Debt Securities Available-for-Sale With Maturities	2,021
Total Debt Securities Available-for-Sale, Amortized Cost	2,021	7,603
Fair Value
Debt Securities Available-for-Sale With Maturities	2,025
Total Debt Securities Available-for-Sale	$ 2,025	$ 7,627