Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 8) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 14,818,295,000	$ 12,309,385,000
Covered Loans Allowance
Balance, beginning of period	64,565,000	67,389,000
Provision for losses	45,346,000	43,646,000	76,218,000
Charge-offs		(325,000)
Reduction in allowance due to loan removals	(65,130,000)	(46,145,000)
Balance, end of period	44,781,000	64,565,000	67,389,000
Acquired covered loans on nonaccrual status		400,000
Covered loans 30 to 89 days delinquent	43,400,000	49,100,000
Covered loans 90 days or more past due on accrual status	112,400,000	330,200,000
Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	6,211,353,000	4,846,594,000
Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,829,694,000	2,110,749,000
Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,962,205,000	3,763,218,000
Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,465,474,000	1,581,796,000
Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,496,731,000	2,181,422,000
Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	222,780,000	315,609,000
Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	165,615,000	217,861,000
Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	57,165,000	97,748,000
Equity lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	711,750,000	741,081,000
Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	142,793,000	132,647,000
Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	437,000	605,000
Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	142,356,000	132,042,000
Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	737,720,000	399,487,000
Nonclassified
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	14,415,241,000	11,834,998,000
Nonclassified | Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	6,073,459,000	4,732,663,000
Nonclassified | Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,705,469,000	1,930,001,000
Nonclassified | Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,928,719,000	3,728,878,000
Nonclassified | Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,449,270,000	1,565,420,000
Nonclassified | Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,479,449,000	2,163,458,000
Nonclassified | Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	146,681,000	191,633,000
Nonclassified | Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	119,189,000	147,916,000
Nonclassified | Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	27,492,000	43,717,000
Nonclassified | Equity lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	685,011,000	724,045,000
Nonclassified | Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	142,099,000	131,522,000
Nonclassified | Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	437,000	601,000
Nonclassified | Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	141,662,000	130,921,000
Nonclassified | Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	733,803,000	396,256,000
Classified
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	403,054,000	474,387,000
Classified | Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	137,894,000	113,931,000
Classified | Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	124,225,000	180,748,000
Classified | Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	33,486,000	34,340,000
Classified | Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	16,204,000	16,376,000
Classified | Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	17,282,000	17,964,000
Classified | Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	76,099,000	123,976,000
Classified | Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	46,426,000	69,945,000
Classified | Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	29,673,000	54,031,000
Classified | Equity lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	26,739,000	17,036,000
Classified | Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	694,000	1,125,000
Classified | Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans		4,000
Classified | Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	694,000	1,121,000
Classified | Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 3,917,000	$ 3,231,000