Securities - Contractual Maturities of Debt Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 30,673
Due after one year through five years	137,885
Due after five years through ten years	66,445
Due after ten years	23,241
Debt Securities Available-for-sale, Maturity, Amortized Cost	258,244
Debt Securities, Available-for-Sale, Amortized Cost	673,638	$ 685,170
Fair Value
Due in one year or less	30,661
Due after one year through five years	138,709
Due after five years through ten years	68,060
Due after ten years	24,265
Debt Securities Available-for-sale, Maturity, Fair Value	261,695
Debt Securities, Available-for-Sale, Fair Value	675,922	680,056
Commercial mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	239,196
Debt Securities, Available-for-Sale, Amortized Cost	239,196	251,660
Fair Value
Debt Securities Available-for-Sale With Maturities	237,554
Debt Securities, Available-for-Sale, Fair Value	237,554	246,784
Residential mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	22,481
Debt Securities, Available-for-Sale, Amortized Cost	22,481	24,564
Fair Value
Debt Securities Available-for-Sale With Maturities	22,514
Debt Securities, Available-for-Sale, Fair Value	22,514	24,350
Collateralized mortgage obligations of U.S. government corporations and agencies
Amortized Cost
Debt Securities Available-for-Sale With Maturities	153,717
Debt Securities, Available-for-Sale, Amortized Cost	153,717	149,849
Fair Value
Debt Securities Available-for-Sale With Maturities	154,159
Debt Securities, Available-for-Sale, Fair Value	$ 154,159	$ 148,659