Securities - Contractural Maturities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Securities Available-for-Sale, Amortized Cost
Due in one year or less	$ 11,600
Due after one year through five years	1,847
Due after five years through ten years	18,178
Due after ten years	203,280
Debt securities excluding securities not due at a single maturity date	234,905
Total	$ 571,208	$ 545,433
Securities Available-for-Sale, Weighted Average Yield
Due in one year or less (as a percent)	2.60%
Due after one year through five years (as a percent)	4.65%
Due after five years through ten years (as a percent)	2.88%
Due after ten years (as a percent)	3.01%
Debt securities (as a percent)	2.99%
Total (as a percent)	2.82%
Securities Available-for-Sale, Fair Value
Due in one year or less	$ 11,636
Due after one year through five years	1,844
Due after five years through ten years	18,202
Due after ten years	206,452
Debt securities	238,134
Fair Value	568,227	531,838
Collateralized mortgage obligations
Securities Available-for-Sale, Amortized Cost
Total	102,717	174,352
Securities Available-for-Sale, Fair Value
Fair Value	100,913	170,927
Asset-backed securities
Securities Available-for-Sale, Amortized Cost
Securities not due at a single maturity date	144,812
Total	$ 144,812	146,391
Securities Available-for-Sale, Weighted Average Yield
Securities not due at a single maturity date, Weighted Average Yield (as a percent)	2.21%
Securities Available-for-Sale, Fair Value
Securities not due at a single maturity date	$ 140,385
Fair Value	140,385	138,407
Collateralized loan obligations
Securities Available-for-Sale, Amortized Cost
Securities not due at a single maturity date	67,735
Total	$ 67,735	102,504
Securities Available-for-Sale, Weighted Average Yield
Securities not due at a single maturity date, Weighted Average Yield (as a percent)	4.01%
Securities Available-for-Sale, Fair Value
Securities not due at a single maturity date	$ 67,949
Fair Value	67,949	$ 101,637
Mortgage-backed and collateralized mortgage obligations
Securities Available-for-Sale, Amortized Cost
Securities not due at a single maturity date	$ 123,756
Securities Available-for-Sale, Weighted Average Yield
Securities not due at a single maturity date, Weighted Average Yield (as a percent)	2.54%
Securities Available-for-Sale, Fair Value
Securities not due at a single maturity date	$ 121,759