Loans and Allowance for Credit Losses Loans Modified Under Troubled Debt Restructurings (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Total Accruing Troubled Debt Restructurings	$ 63,135	$ 59,560
Non-accrual TDRs (1)	28,742	27,850
Total TDRs	91,877	87,410
Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Total Accruing Troubled Debt Restructurings	26,193	27,617
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Total Accruing Troubled Debt Restructurings	14,439	15,957
Real-estate - home equity
Financing Receivable, Modifications [Line Items]
Total Accruing Troubled Debt Restructurings	14,789	8,594
Commercial - secured
Financing Receivable, Modifications [Line Items]
Total Accruing Troubled Debt Restructurings	7,512	6,627
Construction - commercial residential
Financing Receivable, Modifications [Line Items]
Total Accruing Troubled Debt Restructurings	169	726
Consumer - direct
Financing Receivable, Modifications [Line Items]
Total Accruing Troubled Debt Restructurings	$ 33	$ 39