Loans, Loans Modified in a Troubled Debt Restructuring (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) loan	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	77	131	211
Recorded Investment	$ 9,426	$ 9,270	$ 41,131
Unpaid Principal Balance	$ 11,900	$ 9,631	$ 42,765
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	8	8	12
Recorded Investment	$ 3,991	$ 1,509	$ 2,219
Unpaid Principal Balance	$ 6,339	$ 1,526	$ 2,900
Commercial real estate — owner occupied
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	2	1	5
Recorded Investment	$ 690	$ 116	$ 3,694
Unpaid Principal Balance	$ 690	$ 122	$ 3,901
Commercial real estate — investor
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	5
Recorded Investment	$ 0	$ 0	$ 21,573
Unpaid Principal Balance	$ 0	$ 0	$ 21,640
Real estate construction
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	1	4
Recorded Investment	$ 0	$ 65	$ 78
Unpaid Principal Balance	$ 0	$ 91	$ 79
Residential mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	45	63	97
Recorded Investment	$ 4,238	$ 5,535	$ 10,464
Unpaid Principal Balance	$ 4,364	$ 5,792	$ 10,996
Home equity
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	22	57	88
Recorded Investment	$ 507	$ 2,030	$ 3,103
Unpaid Principal Balance	$ 507	$ 2,084	$ 3,249
Other consumer
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	1	0
Recorded Investment	$ 0	$ 15	$ 0
Unpaid Principal Balance	$ 0	$ 16	$ 0