Goodwill and Core Deposit Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Sep. 30, 2017
Goodwill
Beginning of period			$ 85,291	$ 85,291	$ 85,291
End of the period	$ 85,291		85,291		85,291
Core Deposit Intangibles RollForward
Beginning of period			9,975	11,562	11,562
Less amortization			(1,140)	(1,206)	(1,587)
End of period	8,835		8,835		9,975
Amortization of Intangible Assets			1,140	1,206	1,587
Expected future amortization expense
Finite-Lived Intangible Assets, Net, Total	8,835		9,975	11,562	$ 11,562	$ 8,835
Core deposit intangibles
Core Deposit Intangibles RollForward
Less amortization	(380)	$ (402)	(1,100)	(1,200)
End of period	8,835		8,835
Amortization of Intangible Assets	380	$ 402	1,100	$ 1,200
Expected future amortization expense
2017						332
2018						1,196
2019						1,080
2020						992
2021						905
Thereafter						4,330
Finite-Lived Intangible Assets, Net, Total	$ 8,835		$ 8,835			$ 8,835
Core deposit intangibles | Minimum
Core Deposit Intangibles RollForward
Finite-Lived Intangible Asset, Useful Life			6 years
Core deposit intangibles | Maximum
Core Deposit Intangibles RollForward
Finite-Lived Intangible Asset, Useful Life			19 years