Loans Loans - Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract
Troubled Debt Restructurings
Number of Contracts (in contract) | Contract	18	12	77	28
Pre-Modification Outstanding Recorded Investment	$ 19,642	$ 10,235	$ 83,846	$ 24,481
Post-Modification Outstanding Recorded Investment	$ 18,766	$ 10,291	$ 78,400	$ 23,680
Commercial and industrial
Troubled Debt Restructurings
Number of Contracts (in contract) | Contract	10	7	61	12
Pre-Modification Outstanding Recorded Investment	$ 12,522	$ 6,389	$ 57,338	$ 11,700
Post-Modification Outstanding Recorded Investment	$ 11,655	$ 6,248	$ 52,694	$ 11,088
Commercial real estate
Troubled Debt Restructurings
Number of Contracts (in contract) | Contract	6	3	10	6
Pre-Modification Outstanding Recorded Investment	$ 6,559	$ 3,745	$ 24,994	$ 10,404
Post-Modification Outstanding Recorded Investment	$ 6,554	$ 3,948	$ 24,211	$ 10,252
Residential mortgage
Troubled Debt Restructurings
Number of Contracts (in contract) | Contract	2	1	6	8
Pre-Modification Outstanding Recorded Investment	$ 561	$ 78	$ 1,514	$ 2,300
Post-Modification Outstanding Recorded Investment	$ 557	$ 77	$ 1,495	$ 2,271
Commercial real estate | Commercial real estate
Troubled Debt Restructurings
Number of Contracts (in contract) | Contract	4	1	7	4
Pre-Modification Outstanding Recorded Investment	$ 5,931	$ 1,667	$ 23,806	$ 8,325
Post-Modification Outstanding Recorded Investment	$ 5,929	$ 1,870	$ 23,217	$ 8,174
Construction | Commercial real estate
Troubled Debt Restructurings
Number of Contracts (in contract) | Contract	2	2	3	2
Pre-Modification Outstanding Recorded Investment	$ 628	$ 2,078	$ 1,188	$ 2,079
Post-Modification Outstanding Recorded Investment	$ 625	$ 2,078	$ 994	$ 2,078