Loans and Allowance for Credit Losses Troubled Debt Restructuring Modification (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) loans	Dec. 31, 2015 USD ($) loans	Dec. 31, 2014 USD ($) loans
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	158	96	86
Post-Modification Recorded Investment	$ 12,378	$ 14,416	$ 16,397
Number of Loans, modified during the year that had a post-modification default	45	29	31
Recorded Investment, modified during the year that had a post-modification default	$ 5,996	$ 5,116	$ 7,063
Real estate – commercial mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	1	4	2
Recorded Investment, modified during the year that had a post-modification default	$ 118	$ 359	$ 1,660
Real estate – commercial mortgage | Extend maturity with rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	5	1
Post-Modification Recorded Investment	$ 0	$ 2,014	$ 60
Real estate – commercial mortgage | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	4	7
Post-Modification Recorded Investment	$ 0	$ 639	$ 6,781
Real estate – residential mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	8	4	11
Recorded Investment, modified during the year that had a post-modification default	$ 1,500	$ 445	$ 1,430
Real estate – residential mortgage | Extend maturity with rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	4	2
Post-Modification Recorded Investment	$ 0	$ 750	$ 390
Real estate – residential mortgage | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	2	3	2
Post-Modification Recorded Investment	$ 315	$ 262	$ 210
Real estate – residential mortgage | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	6	7	19
Post-Modification Recorded Investment	$ 981	$ 2,508	$ 1,807
Commercial - secured
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	6	8	4
Recorded Investment, modified during the year that had a post-modification default	$ 2,497	$ 3,549	$ 1,208
Commercial - secured | Extend maturity with rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	2	3
Post-Modification Recorded Investment	$ 0	$ 127	$ 315
Commercial - secured | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	10	9	8
Post-Modification Recorded Investment	$ 3,801	$ 3,785	$ 1,640
Commercial - unsecured
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default | loans	1	0	0
Recorded Investment, modified during the year that had a post-modification default	$ 26	$ 0	$ 0
Commercial - unsecured | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	2	1	0
Post-Modification Recorded Investment	$ 103	$ 38	$ 0
Real estate – home equity
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	28	13	11
Recorded Investment, modified during the year that had a post-modification default	$ 1,836	$ 763	$ 961
Real estate – home equity | Extend maturity with rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	2	0
Post-Modification Recorded Investment	$ 0	$ 36	$ 0
Real estate – home equity | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	89	3	0
Post-Modification Recorded Investment	$ 4,484	$ 203	$ 0
Real estate – home equity | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	47	52	30
Post-Modification Recorded Investment	$ 2,671	$ 2,501	$ 1,551
Construction - commercial residential
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	0	0	2
Recorded Investment, modified during the year that had a post-modification default	$ 0	$ 0	$ 1,803
Construction - commercial residential | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	1	3
Post-Modification Recorded Investment	$ 0	$ 1,535	$ 3,616
Consumer - direct
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	0	0	1
Recorded Investment, modified during the year that had a post-modification default	$ 0	$ 0	$ 1
Consumer - direct | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	1	2	7
Post-Modification Recorded Investment	$ 2	$ 6	$ 7
Consumer - indirect:
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default | loans	1	0	0
Recorded Investment, modified during the year that had a post-modification default	$ 19	$ 0	$ 0
Consumer - indirect: | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	1	1	4
Post-Modification Recorded Investment	$ 21	$ 12	$ 20