Securities - Contractual Maturities of Debt Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 73,193
Due after one year through five years	103,058
Due after five years through ten years	55,237
Due after ten years	15,090
Debt Securities Available-for-sale, Maturity, Amortized Cost	246,578
Debt Securities, Available-for-Sale, Amortized Cost	650,917	$ 685,170
Fair Value
Due in one year or less	73,425
Due after one year through five years	105,407
Due after five years through ten years	58,034
Due after ten years	15,867
Debt Securities Available-for-sale, Maturity, Fair Value	252,733
Debt Securities, Available-for-Sale, Fair Value	664,520	680,056
Collateralized mortgage obligations of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	151,759
Debt Securities, Available-for-Sale, Amortized Cost	151,759	149,849
Fair Value
Debt Securities Available-for-Sale With Maturities	155,010
Debt Securities, Available-for-Sale, Fair Value	155,010	148,659
Residential mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	18,504
Debt Securities, Available-for-Sale, Amortized Cost	18,504	24,564
Fair Value
Debt Securities Available-for-Sale With Maturities	18,826
Debt Securities, Available-for-Sale, Fair Value	18,826	24,350
Commercial mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	234,076
Debt Securities, Available-for-Sale, Amortized Cost	234,076	251,660
Fair Value
Debt Securities Available-for-Sale With Maturities	237,951
Debt Securities, Available-for-Sale, Fair Value	$ 237,951	$ 246,784