Loans and Allowance for Credit Losses Troubled Debt Restructuring Modification (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) loans	Dec. 31, 2017 USD ($) loans	Dec. 31, 2016 USD ($) loans
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	117	143	158
Post-Modification Recorded Investment	$ 18,375	$ 29,634	$ 12,378
Number of Loans, modified during the year that had a post-modification default	38	40	45
Recorded Investment, modified during the year that had a post-modification default	$ 4,963	$ 5,875	$ 5,996
Real estate – commercial mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	2	2	1
Recorded Investment, modified during the year that had a post-modification default	$ 448	$ 549	$ 118
Real estate – commercial mortgage | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	6	9	0
Post-Modification Recorded Investment	$ 8,261	$ 2,899	$ 0
Real estate – commercial mortgage | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	1	0
Post-Modification Recorded Investment	$ 0	$ 12	$ 0
Real estate – residential mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	5	5	8
Recorded Investment, modified during the year that had a post-modification default	$ 717	$ 577	$ 1,500
Real estate – residential mortgage | Extend maturity with rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	4	2	0
Post-Modification Recorded Investment	$ 451	$ 468	$ 0
Real estate – residential mortgage | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	2	5	2
Post-Modification Recorded Investment	$ 345	$ 1,044	$ 315
Real estate – residential mortgage | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	1	3	6
Post-Modification Recorded Investment	$ 5	$ 392	$ 981
Commercial - secured
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	1	6	7
Recorded Investment, modified during the year that had a post-modification default	$ 2,163	$ 1,571	$ 2,523
Commercial - secured | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	8	23	12
Post-Modification Recorded Investment	$ 4,226	$ 15,058	$ 3,904
Commercial - secured | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	1	0
Post-Modification Recorded Investment	$ 0	$ 490	$ 0
Real estate – home equity
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	30	25	28
Recorded Investment, modified during the year that had a post-modification default	$ 1,635	$ 1,575	$ 1,836
Real estate – home equity | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	85	69	89
Post-Modification Recorded Investment	$ 4,549	$ 5,843	$ 4,484
Real estate – home equity | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	11	28	47
Post-Modification Recorded Investment	$ 538	$ 1,813	$ 2,671
Construction - commercial residential
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	0	1	0
Recorded Investment, modified during the year that had a post-modification default	$ 0	$ 1,192	$ 0
Construction - commercial residential | Extend maturity without rate concession
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	1	0
Post-Modification Recorded Investment	$ 0	$ 1,204	$ 0
Construction - commercial residential | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	1	0
Post-Modification Recorded Investment	$ 0	$ 411	$ 0
Construction - other
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default	0	1	0
Recorded Investment, modified during the year that had a post-modification default	$ 0	$ 411	$ 0
Consumer - direct | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of loans modified during the year (loans) | loans	0	0	2
Post-Modification Recorded Investment	$ 0	$ 0	$ 23
Consumer - indirect:
Financing Receivable, Modifications [Line Items]
Number of Loans, modified during the year that had a post-modification default | loans	0	0	1
Recorded Investment, modified during the year that had a post-modification default	$ 0	$ 0	$ 19