Loans and Allowance for Loan Losses (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended					12 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Substandard [Member] D	Jun. 30, 2012 Loss And Charged Off [Member] D	Jun. 30, 2012 Accruing TDRs With Modifications And Renewals Completed [Member]	Dec. 31, 2011 Accruing TDRs With Modifications And Renewals Completed [Member]	Jun. 30, 2011 Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan substandard period (in days)					90
Retail loan charge-off period (in days)						120
Accruing troubled debt restructuring	$ 687,400,000		$ 687,400,000
Allowance for loan losses allocated to accuring TDRs				668,500,000
Provision for losses on loans	(44,222,000)	(120,159,000)	(110,271,000)	261,905,000			56,400,000	60,700,000
Commercial-type impaired loans									$ 1,000,000