Allowance for Loan Losses Allowance for Losses on Lending-Related Commitments and Impaired Loans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) contracts Rate	Dec. 31, 2015 USD ($) contracts Rate	Dec. 31, 2014 USD ($) contracts Rate
Financing Receivable, Allowance for Credit Losses [Line Items]
Average recorded investment	$ 105,423,000	$ 107,170,000	$ 135,000,000
Impaired Financing Receivable, Interest Income, Accrual Method	5,485,000	6,198,000	$ 7,200,000
Financing Receivable, Modifications, Recorded Investment	$ 41,708,000	$ 51,853,000
Number of loans | contracts	21	12	21
Allowance for loan losses related to impaired loans	$ 6,377,000	$ 6,380,000
Balance of loans	$ 12,897,000	$ 2,034,000	$ 11,967,000
Financing Receivables, Modifications, Weighted Average Extension Term	19 months	45 months	19 months
Weighted Average Stated Interest Rate Basis Points | Rate	0.34%	3.58%	1.70%
Financing Receivables, Modifications, Weighted Average Interest Only Term	7 months	17 months	7 months
Loan Forgiveness	$ 300,000	$ 0	$ 0
Financing Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of loans | contracts	89
Allowance for loan losses related to impaired loans	$ 2,700,000
Loans and Leases Receivable, Impaired, Interest Income Recognized, Change in Present Value Attributable to Passage of Time	421,000	$ 573,000
Residential Real Estate | Financing Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
Other real estate owned	9,400,000
In process other real estate owned	$ 12,100,000