Loans - Interest Recognized and Cash Basis Interest Earned on Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Interest Recognized and Cash Basis Interest Earned on Impaired Loans
Average of impaired loans during the period	$ 3,547	$ 4,567	$ 3,955	$ 4,997
Interest income during impairment	3		3
Commercial
Interest Recognized and Cash Basis Interest Earned on Impaired Loans
Average of impaired loans during the period	2,010	2,200
Real estate
Interest Recognized and Cash Basis Interest Earned on Impaired Loans
Average of impaired loans during the period				3
Consumer
Interest Recognized and Cash Basis Interest Earned on Impaired Loans
Average of impaired loans during the period	1	3	2
Commercial | Real estate
Interest Recognized and Cash Basis Interest Earned on Impaired Loans
Average of impaired loans during the period			2,625	1,771
CRE | Real estate
Interest Recognized and Cash Basis Interest Earned on Impaired Loans
Average of impaired loans during the period	501	1,644	583	2,298
Land and construction | Real estate
Interest Recognized and Cash Basis Interest Earned on Impaired Loans
Average of impaired loans during the period	641	204	419	210
Interest income during impairment	3		3
Home equity | Real estate
Interest Recognized and Cash Basis Interest Earned on Impaired Loans
Average of impaired loans during the period	$ 394	$ 516	$ 326	$ 715