Assets & Liability Derivative Positions & the Potential Effect of Netting Arrangements - Current Quarter (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 28,061	$ 22,390
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Asset	28,061	22,390
Derivative, Collateral, Obligation to Return Securities	4	272
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	28,057	22,118
Derivative Liability, Fair Value, Gross Liability	201,540	225,824
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	201,540	225,824
Derivative, Collateral, Right to Reclaim Securities	4	272
Derivative, Collateral, Right to Reclaim Cash	197,199	221,296
Derivative Liability, Fair Value, Amount Offset Against Collateral	4,337	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	5,370	5,570
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	5,370	5,570
Derivative, Collateral, Right to Reclaim Securities	0	0
Derivative, Collateral, Right to Reclaim Cash	5,370	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	23,700	18,383
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Asset	23,700	18,383
Derivative, Collateral, Obligation to Return Securities	4	272
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	23,696	18,111
Derivative Liability, Fair Value, Gross Liability	23,699	18,380
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	23,699	18,380
Derivative, Collateral, Right to Reclaim Securities	4	272
Derivative, Collateral, Right to Reclaim Cash	23,691	17,836
Derivative Liability, Fair Value, Amount Offset Against Collateral	4	272
Customer foreign exchange contracts
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	4,361	4,007
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Asset	4,361	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	4,361	4,007
Derivative Liability, Fair Value, Gross Liability	4,333	3,984
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	4,333	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	4,333	3,984
Customer repurchase agreements and other short-term borrowings(c)
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	118,138	147,890
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	118,138	147,890
Derivative, Collateral, Right to Reclaim Securities	0	0
Derivative, Collateral, Right to Reclaim Cash	118,138	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	50,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	50,000	50,000
Derivative, Collateral, Right to Reclaim Securities	0	0
Derivative, Collateral, Right to Reclaim Cash	50,000	50,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 0	$ 0