Securities - Amortized Costs and Fair Values of Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 396,896	$ 196,504
Gross Unrealized Gains	1,412	434
Gross Unrealized Losses	(3,268)	(2,848)
Estimated Fair Value	395,040	194,090
U.S. Government agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	26,262	5,106
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(203)	(112)
Estimated Fair Value	26,059	4,994
Municipals
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	101,037	45,392
Gross Unrealized Gains	1,208	172
Gross Unrealized Losses	(836)	(1,205)
Estimated Fair Value	101,409	44,359
Mortgage backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	248,702	120,794
Gross Unrealized Gains	158	177
Gross Unrealized Losses	(1,945)	(1,164)
Estimated Fair Value	246,915	119,807
Asset backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,892	13,105
Gross Unrealized Gains	4	17
Gross Unrealized Losses	(173)	(258)
Estimated Fair Value	8,723	12,864
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,527	8,631
Gross Unrealized Gains	25	35
Gross Unrealized Losses	(1)	0
Estimated Fair Value	8,551	8,666
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,976	1,976
Gross Unrealized Gains	17	33
Gross Unrealized Losses	0	0
Estimated Fair Value	1,993	2,009
CRA mutual fund
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,500	1,500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(110)	(109)
Estimated Fair Value	$ 1,390	$ 1,391