Assets & Liability Derivative Positions & the Potential Effect of Netting Arrangements - Current Quarter (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 29,867	$ 22,390
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Asset	29,867	22,390
Derivative, Collateral, Obligation to Return Securities	0	272
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	29,867	22,118
Derivative Liability, Fair Value, Gross Liability	172,640	225,824
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	172,640	225,824
Derivative, Collateral, Right to Reclaim Securities	0	272
Derivative, Collateral, Right to Reclaim Cash	172,006	221,296
Derivative Liability, Fair Value, Amount Offset Against Collateral	634	4,256
Interest rate swaps
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Asset	0	0
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	0	0
Derivative Liability, Fair Value, Gross Liability	4,355	5,570
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	4,355	5,570
Derivative, Collateral, Right to Reclaim Securities	0	0
Derivative, Collateral, Right to Reclaim Cash	4,355	5,570
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	0
Loan level swaps
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	29,205	18,383
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Asset	29,205	18,383
Derivative, Collateral, Obligation to Return Securities	0	272
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	29,205	18,111
Derivative Liability, Fair Value, Gross Liability	29,202	18,380
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	29,202	18,380
Derivative, Collateral, Right to Reclaim Securities	0	272
Derivative, Collateral, Right to Reclaim Cash	29,202	17,836
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	272
Customer foreign exchange contracts
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	662	4,007
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Asset	662	4,007
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	662	4,007
Derivative Liability, Fair Value, Gross Liability	634	3,984
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	634	3,984
Derivative, Collateral, Right to Reclaim Securities	0	0
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	634	3,984
Customer repurchase agreements and other short-term borrowings(c)
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	138,449	147,890
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	138,449	147,890
Derivative, Collateral, Right to Reclaim Securities	0	0
Derivative, Collateral, Right to Reclaim Cash	138,449	147,890
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 0	0
Wholesale repurchase agreements
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability		50,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		0
Derivative Liability		50,000
Derivative, Collateral, Right to Reclaim Securities		0
Derivative, Collateral, Right to Reclaim Cash		50,000
Derivative Liability, Fair Value, Amount Offset Against Collateral		$ 0