Derivatives (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Collateral cash receivables	$ 101,800,000	$ 163,200,000
Collateral cash payables	82,500,000	124,300,000
Total trading revenues	49,600,000	68,000,000
Noncallable senior debt maturing date	2015-12-01
Other Long-term Debt	1,507,048,000	2,197,864,000	1,739,859,000
Hedged amount of foreign currency denominated loans	800,000	600,000
Visa Class B Shares [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liabilities related to sale	4,900,000	2,100,000
Parent Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged held-to-maturity trust preferred loans principal balance	6,500,000	21,500,000
Derivative Instruments With Accelerated Termination Provisions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Collateral received	200,000,000	255,300,000
Securities posted collateral	27,800,000	37,800,000
Net fair value of derivative assets with adjustable posting thresholds	121,900,000	208,600,000
Net fair value of derivative liabilities with adjustable posting thresholds	22,600,000	35,800,000
Long Term Debt Hedged With Fair Value Interest Rate Derivatives Using Shortcut Method [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net fair value of interest rate derivatives hedging	34,100,000	60,500,000
Other Long-term Debt	554,000,000	904,000,000
Long Term Debt Hedged With Fair Value Interest Rate Derivatives Using Long Haul Method [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net fair value of interest rate derivatives hedging	16,000,000	24,600,000
Other Long-term Debt	500,000,000	500,000,000
Subordinated Debentures Subject To Mandatory Redemption Amount [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net fair value of interest rate derivatives hedging subordinated debt	16,400,000	7,400,000
Other Long-term Debt	200,000,000	200,000,000
Hedge Of Held To Maturity Trust Preferred Loans [Member] | Parent Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net fair value of interest rate derivatives hedging subordinated debt	900,000	1,500,000
Additional Derivative Agreements [Member] | Derivative Instruments With Adjustable Collateral Posting Thresholds [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Collateral received	200,000,000	255,300,000
Securities posted collateral	92,500,000	153,900,000
Net fair value of derivative assets with adjustable posting thresholds	121,900,000	210,100,000
Net fair value of derivative liabilities with adjustable posting thresholds	$ 90,300,000	$ 156,400,000