Loans and Allowance for Loan Losses (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in allocated allowance			$ 23,000,000
Average recorded investment in impaired loans	585,494,000	967,452,000	585,494,000	967,452,000
Interest income recognized	3,987,000		7,980,000	0	21,114,000
Average recorded investment in impaired loans	650,724,000		720,422,000		952,232,000
Interest income recognized for accruing TDRs	4,000,000	5,400,000	8,000,000	10,800,000
Accruing troubled debt restructuring	444,100,000		444,100,000		556,400,000
Allowance for loan losses	277,783,000	334,880,000	277,783,000	334,880,000	307,560,000	300,871,000	351,772,000	373,405,000
Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan substandard period (in days)			90 days
Loss And Charged Off [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan charge-off period (in days)			120 days
Accruing TDRs With Modifications And Renewals Completed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	24,300,000		24,300,000		27,700,000
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial-type impaired loans			$ 1,000,000