Parent Company Only Financial Statements Condensed statements of income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Income before income taxes	$ 10,660	$ 8,120	$ 7,553	$ 7,447	$ 7,238	$ 5,642	$ 6,508	$ 6,342	$ 33,780	$ 25,730	$ 24,715
Income tax benefit	(3,863)	(2,812)	(2,624)	(2,641)	(2,584)	(1,979)	(2,352)	(2,303)	(11,940)	(9,218)	(9,254)
Net income	$ 6,797	$ 5,308	$ 4,929	$ 4,806	$ 4,654	$ 3,663	$ 4,156	$ 4,039	21,840	16,512	15,461
Other Comprehensive Income (Loss), Net of Tax									(6,484)	1,598	7,505
Comprehensive income									15,356	18,110	22,966
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends from subsidiaries									19,475	6,094	7,900
Other income									66	66	65
Total income									19,541	6,160	7,965
Operating expenses									3,491	2,556	2,425
Income before income taxes									16,050	3,604	5,540
Income tax benefit									1,073	974	948
Income before equity in undistributed earnings of subsidiaries									17,123	4,578	6,488
Equity in undistributed earnings of subsidiaries									4,717	11,934	8,973
Net income									21,840	16,512	15,461
Other Comprehensive Income (Loss), Net of Tax										1,598	7,505
Comprehensive income									$ 15,356	$ 18,110	$ 22,966