Investment Securities - By Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Amortized Cost
One Year or Less	$ 5,740
More than One Year to Five Years	42,052
More than Five Years to Ten Years	197,572
More than Ten Years	459,933
Total	705,297
Fair Value
One Year or Less	5,737
More than One Year to Five Years	42,360
More than Five Years to Ten Years	200,107
More than Ten Years	462,582
Total	710,786
Amortized Cost
One Year or Less	5,740
More than One Year to Five Years	42,052
More than Five Years to Ten Years	197,572
More than Ten Years	452,183
Total	697,547	$ 385,662
Fair Value
One Year or Less	5,737
More than One Year to Five Years	42,360
More than Five Years to Ten Years	200,107
More than Ten Years	454,879
Total	703,083	380,963
Amortized Cost
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	0
More than Ten Years	7,750
Amortized Cost	7,750	8,565
Fair Value
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	0
More than Ten Years	7,703
Total	7,703	8,461
Agency
Amortized Cost
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	15,123
More than Ten Years	39,265
Total	54,388
Fair Value
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	15,248
More than Ten Years	39,823
Total	55,071
Corporate
Amortized Cost
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	53,498
More than Ten Years	0
Total	53,498	37,475
Fair Value
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	54,349
More than Ten Years	0
Total	54,349	37,642
Municipal bonds
Amortized Cost
One Year or Less	3,104
More than One Year to Five Years	35,725
More than Five Years to Ten Years	75,712
More than Ten Years	132,701
Total	247,242	120,155
Fair Value
One Year or Less	3,107
More than One Year to Five Years	36,012
More than Five Years to Ten Years	77,010
More than Ten Years	135,949
Total	252,078	118,803
Collateralized mortgage obligation: residential
Amortized Cost
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	3,613
More than Ten Years	42,482
Total	46,095	31,536
Fair Value
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	3,661
More than Ten Years	42,660
Total	46,321	31,388
Mortgage-backed securities
Amortized Cost
One Year or Less	2,636
More than One Year to Five Years	6,327
More than Five Years to Ten Years	49,626
More than Ten Years	237,735
Total	296,324	196,496
Fair Value
One Year or Less	2,630
More than One Year to Five Years	6,348
More than Five Years to Ten Years	49,839
More than Ten Years	236,447
Total	295,264	193,130
Amortized Cost
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	0
More than Ten Years	6,586
Amortized Cost	6,586	7,375
Fair Value
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	0
More than Ten Years	6,539
Total	6,539	$ 7,271
Other
Amortized Cost
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	0
More than Ten Years	1,164
Amortized Cost	1,164
Fair Value
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	0
More than Ten Years	1,164
Total	$ 1,164