Loans (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings loans	$ 368,800,000	$ 303,300,000
Allowance for loan losses	265,218,000	346,016,000	276,963,000	384,351,000
Average balance of impaired loans	467,682,000	483,807,000
Interest income recognized on impaired loan	1,631,000	1,706,000
Permanent Mortgage Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	25,448,000	32,572,000	24,928,000	26,194,000
TDRS Maturities	40 years
Loans Held For Sale [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings loans	182,100,000	126,300,000
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	41.00%
Consumer Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	35.00%
Allowance for loan losses	131,417,000	141,647,000	128,949,000	165,077,000
TDRS Maturities	30 years
Bank Related And Trups [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of commercial loan portfolio	6.00%
Concentration risk, percentage	3.00%
Commercial loans	500,000,000
Modified Loans Classified As Tdr [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	64,600,000	49,900,000
Ratio of the allowance for loan losses to loans	18.00%	16.00%
Loans To Mortgage Companies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of commercial loan portfolio	14.00%
Concentration risk, percentage	7.00%
Commercial loans	1,100,000,000
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average balance of impaired loans	168,068,000	276,345,000
Interest income recognized on impaired loan	229,000	401,000
Credit Card And Other Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	7,110,000	6,170,000	6,898,000	7,081,000
Credit Card Portfolio Class [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit card workout program, granted rate reduction	0.00%
Credit card workout program, term extension	5 years
Heloc, Real Estate Installment And Permanent Mortgage Classes [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer TDR, reduction of interest rate by increment, basis points	0.25%
Modified interest rate time period	5 years
Maximum [Member] | Commercial Loan P D Grade Sixteen [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	16
Maximum [Member] | Commercial Loan L G D Grade Twelve [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	12
Maximum [Member] | Bank Related And Trups [Member] | Commercial Loan P D Grade Thirteen [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	13
Maximum [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period	12 months
Maximum [Member] | Credit Card Portfolio Class [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment reductions, time period	1 year
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	1,000,000
Minimum [Member] | Commercial Loan P D Grade One [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	1
Minimum [Member] | Commercial Loan P D Grade Thirteen [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	500,000
Minimum [Member] | Commercial Loan L G D Grade One [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	1
Minimum [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period	6 months
Minimum [Member] | Commercial Portfolio Segment [Member] | Non Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired commercial loans	$ 1,000,000
Minimum [Member] | Credit Card Portfolio Class [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment reductions, time period	6 months
Minimum [Member] | Heloc, Real Estate Installment And Permanent Mortgage Classes [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate	1.00%
PD Grade | Commercial Loan P D Grade Twelve [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	12
PD Grade | Commercial Loan P D Grade Thirteen [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	13
PD Grade | Commercial Loan P D Grade Fourteen [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	14
PD Grade | Commercial Loan P D Grade Fifteen [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	15
PD Grade | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Time period of default probability	1 year