Securities - Contractual Maturities of Debt Securities (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Amortized Cost
Due in one year or less		$ 84,687
Due after one year through five years		100,877
Due after five years through ten years		65,732
Due after ten years		31,144
Debt Securities Available-for-sale, Maturity, Amortized Cost		282,440
Debt Securities, Available-for-Sale, Amortized Cost	[1]	763,696	$ 768,427
Fair Value
Due in one year or less		85,259
Due after one year through five years		106,112
Due after five years through ten years		68,913
Due after ten years		32,786
Debt Securities Available-for-sale, Maturity, Fair Value		293,070
Debt Securities, Available-for-Sale, Fair Value	[1]	795,966	779,133
Collateralized mortgage obligations of U.S. government corporations and agencies
Amortized Cost
Available-for-Sale Debt Securities With Maturities		180,682
Debt Securities, Available-for-Sale, Amortized Cost		180,682	186,879
Fair Value
Available-for-Sale Debt Securities With Maturities		189,473
Debt Securities, Available-for-Sale, Fair Value		189,472	189,348
Residential mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Available-for-Sale Debt Securities With Maturities		20,391
Debt Securities, Available-for-Sale, Amortized Cost		20,391	22,120
Fair Value
Available-for-Sale Debt Securities With Maturities		21,193
Debt Securities, Available-for-Sale, Fair Value		21,193	22,418
Commercial mortgage-backed securities of U.S. government corporations and agencies
Amortized Cost
Available-for-Sale Debt Securities With Maturities		272,651
Debt Securities, Available-for-Sale, Amortized Cost		272,651	273,771
Fair Value
Available-for-Sale Debt Securities With Maturities		284,679
Debt Securities, Available-for-Sale, Fair Value		284,679	$ 275,870
Corporate Securities
Amortized Cost
Available-for-Sale Debt Securities With Maturities		7,532
Fair Value
Available-for-Sale Debt Securities With Maturities		$ 7,551

[1] Excludes interest receivable of $3.5 million at March 31, 2020 and $3.4 million at December 31, 2019. Interest receivable is included in other assets in the consolidated balance sheets.