Securities - Securities in Continuous Unrealized Loss Position (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) security	Dec. 31, 2016 USD ($)
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	$ 442,039	$ 203,870
Gross Unrealized Losses, Less than 12 Months	(4,117)	(1,585)
Fair Value, Less than 12 Months	437,922	202,285
Amortized Cost, More than 12 Months	18,893	6,995
Gross Unrealized Losses, More than 12 Months	(328)	(96)
Fair Value, More than 12 Months	18,565	6,899
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	2,437	20,692
Gross Unrealized Losses, Less than 12 Months	(27)	(425)
Fair Value, Less than 12 Months	2,410	20,267
Amortized Cost, More than 12 Months	3,872	8,504
Gross Unrealized Losses, More than 12 Months	(104)	(378)
Fair Value, More than 12 Months	$ 3,768	$ 8,126
Investment Securities Continuous Unrealized Loss Position Qualitative Disclosure Abstract
AFS and HTM, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	9
Securities in Unrealized Loss Position, Continuous Unrealized Loss as percent of Amortized Cost	0.98	1.04
SBA guaranteed securities
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	$ 73,878
Gross Unrealized Losses, Less than 12 Months	(350)
Fair Value, Less than 12 Months	73,528
US Treasury and Government
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months		$ 100,517
Gross Unrealized Losses, Less than 12 Months		(403)
Fair Value, Less than 12 Months		100,114
Commercial
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	66,069
Gross Unrealized Losses, Less than 12 Months	(611)
Fair Value, Less than 12 Months	65,458
Residential
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	70,052	60,233
Gross Unrealized Losses, Less than 12 Months	(253)	(405)
Fair Value, Less than 12 Months	69,799	59,828
Amortized Cost, More than 12 Months	5,127	4,121
Gross Unrealized Losses, More than 12 Months	(54)	(25)
Fair Value, More than 12 Months	5,073	4,096
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	2,437	8,551
Gross Unrealized Losses, Less than 12 Months	(27)	(234)
Fair Value, Less than 12 Months	2,410	8,317
Amortized Cost, More than 12 Months	3,872	860
Gross Unrealized Losses, More than 12 Months	(104)	(33)
Fair Value, More than 12 Months	3,768	827
Commercial
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	31,138
Gross Unrealized Losses, Less than 12 Months	(30)
Fair Value, Less than 12 Months	31,108
Residential
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	200,902	29,916
Gross Unrealized Losses, Less than 12 Months	(2,873)	(492)
Fair Value, Less than 12 Months	198,029	29,424
Amortized Cost, More than 12 Months	2,429	2,874
Gross Unrealized Losses, More than 12 Months	(48)	(71)
Fair Value, More than 12 Months	2,381	2,803
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months		12,141
Gross Unrealized Losses, Less than 12 Months		(191)
Fair Value, Less than 12 Months		11,950
Amortized Cost, More than 12 Months		7,644
Gross Unrealized Losses, More than 12 Months		(345)
Fair Value, More than 12 Months		7,299
Corporate debt securities
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months		1,785
Gross Unrealized Losses, Less than 12 Months		(14)
Fair Value, Less than 12 Months		1,771
Obligations of municipal subdivisions
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months		236
Gross Unrealized Losses, Less than 12 Months		(1)
Fair Value, Less than 12 Months		235
CRA qualified investment fund
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months		11,183
Gross Unrealized Losses, Less than 12 Months		(270)
Fair Value, Less than 12 Months		$ 10,913
Amortized Cost, More than 12 Months	11,337
Gross Unrealized Losses, More than 12 Months	(226)
Fair Value, More than 12 Months	$ 11,111