Income Taxes - Components Of The Provision For Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Tax Expense (Benefit)
Federal									$ 2,618	$ 2,874	$ 4,752
State									1,423	674	1,200
Amortization of investment in low income housing tax credit partnerships									2,276	2,868	2,684
Total									6,317	6,416	8,636
Deferred Expense (Benefit)
Federal									3,658	(281)	127
State									346	(83)	21
Amortization of investment in low income housing tax credit partnerships									0	0	0
Total									4,004	(364)	148
Total Expense
Federal									6,276	2,593	4,879
State									1,769	591	1,221
Amortization of investment in low income housing tax credit partnerships									2,276	2,868	2,684
Total	$ 4,085	$ 2,980	$ 1,455	$ 1,801	$ 1,458	$ 1,027	$ 1,868	$ 1,699	$ 10,321	$ 6,052	$ 8,784