Investment Securities - Contractual maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amortized Cost
One Year or Less	$ 1,236
More than One Year to Five Years	29,616
More than Five Years to Ten Years	104,987
More than Ten Years	249,823
Amortized Cost	385,662	$ 279,711
Fair Value
One Year or Less	1,236
More than One Year to Five Years	29,521
More than Five Years to Ten Years	104,379
More than Ten Years	245,827
Total	380,963	280,273
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	8,565
Amortized Cost	8,565	9,642
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	8,461
Total	8,461	9,572
Amortized Cost
One Year or Less	1,236
More than One Year to Five Years	29,616
More than Five Years to Ten Years	104,987
More than Ten Years	258,388
Total	394,227
Fair Value
One Year or Less	1,236
More than One Year to Five Years	29,521
More than Five Years to Ten Years	104,379
More than Ten Years	254,288
Total	389,424
Accumulated other comprehensive income (loss)	(4,699)	562
Accumulated other comprehensive income (loss), net of tax	(2,721)	332
Corporate
Amortized Cost
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	37,475
More than Ten Years	0
Amortized Cost	37,475
Fair Value
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	37,642
More than Ten Years	0
Total	37,642
Municipal bonds
Amortized Cost
One Year or Less	1,236
More than One Year to Five Years	28,450
More than Five Years to Ten Years	43,307
More than Ten Years	47,162
Amortized Cost	120,155	128,546
Fair Value
One Year or Less	1,236
More than One Year to Five Years	28,361
More than Five Years to Ten Years	42,715
More than Ten Years	46,491
Total	118,803	130,245
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	1,392
More than Ten Years	30,144
Amortized Cost	31,536	24,722
Fair Value
One Year or Less	0
More than One Year to Five Years	0
More than Five Years to Ten Years	1,395
More than Ten Years	29,993
Total	31,388	24,543
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	1,190
Amortized Cost	1,190
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	1,190
Total	1,190
Mortgage-backed securities: residential
Amortized Cost
One Year or Less	0
More than One Year to Five Years	1,166
More than Five Years to Ten Years	22,813
More than Ten Years	172,517
Amortized Cost	196,496	126,443
Fair Value
One Year or Less	0
More than One Year to Five Years	1,160
More than Five Years to Ten Years	22,627
More than Ten Years	169,343
Total	193,130	125,485
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	7,375
Amortized Cost	7,375	8,400
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	7,271
Total	$ 7,271	$ 8,330