Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 9) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 15,216,906,000	$ 12,747,902,000	$ 14,818,295,000
Covered Loans Allowance
Balance, beginning of period	44,781,000	64,565,000
Provision for losses	9,892,000	7,466,000
Reduction in allowance due to loan removals	(12,319,000)	(10,560,000)
Balance, end of period	42,354,000	61,471,000
Loans on nonaccrual status	83,275,000		99,787,000
Loans 90 days or more past due on accrual status	1,688,000		981,000
Covered loans
Covered Loans Allowance
Loans on nonaccrual status	0		0
Covered loans 30 to 89 days delinquent	42,600,000		43,400,000
Loans 90 days or more past due on accrual status	102,300,000		112,400,000
Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	6,452,477,000		6,211,353,000
Covered Loans Allowance
Loans on nonaccrual status	7,292,000		9,087,000
Loans 90 days or more past due on accrual status			602,000
Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,937,457,000	2,213,114,000	2,829,694,000
Covered Loans Allowance
Loans on nonaccrual status	23,066,000		33,198,000
Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	4,027,741,000	3,805,807,000	3,962,205,000
Covered Loans Allowance
Loans on nonaccrual status	9,136,000		9,603,000
Loans 90 days or more past due on accrual status	1,033,000		379,000
Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,442,646,000		1,465,474,000
Covered Loans Allowance
Loans on nonaccrual status	4,579,000		4,902,000
Loans 90 days or more past due on accrual status	1,033,000		379,000
Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,585,095,000		2,496,731,000
Covered Loans Allowance
Loans on nonaccrual status	4,557,000		4,701,000
Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	247,114,000	313,409,000	222,780,000
Covered Loans Allowance
Loans on nonaccrual status	39,608,000		40,882,000
Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	193,279,000		165,615,000
Covered Loans Allowance
Loans on nonaccrual status	14,602,000		15,067,000
Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	53,835,000		57,165,000
Covered Loans Allowance
Loans on nonaccrual status	25,006,000		25,815,000
Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	696,679,000	715,997,000	711,750,000
Covered Loans Allowance
Loans on nonaccrual status	4,103,000		6,424,000
Loans 90 days or more past due on accrual status	630,000
Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	137,545,000	125,793,000	142,793,000
Covered Loans Allowance
Loans on nonaccrual status	70,000		473,000
Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	503,000		437,000
Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	137,042,000		142,356,000
Covered Loans Allowance
Loans on nonaccrual status	70,000		473,000
Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	717,893,000		737,720,000
Covered Loans Allowance
Loans on nonaccrual status			120,000
Loans 90 days or more past due on accrual status	25,000
Nonclassified
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	14,825,616,000		14,415,241,000
Nonclassified | Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	6,322,914,000		6,073,459,000
Nonclassified | Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,821,000,000		2,705,469,000
Nonclassified | Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,989,225,000		3,928,719,000
Nonclassified | Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,419,798,000		1,449,270,000
Nonclassified | Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,569,427,000		2,479,449,000
Nonclassified | Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	173,039,000		146,681,000
Nonclassified | Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	148,050,000		119,189,000
Nonclassified | Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	24,989,000		27,492,000
Nonclassified | Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	667,718,000		685,011,000
Nonclassified | Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	137,428,000		142,099,000
Nonclassified | Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	503,000		437,000
Nonclassified | Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	136,925,000		141,662,000
Nonclassified | Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	714,292,000		733,083,000
Classified
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	391,290,000		403,054,000
Classified | Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	129,563,000		137,894,000
Classified | Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	116,457,000		124,225,000
Classified | Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	38,516,000		33,486,000
Classified | Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	22,848,000		16,204,000
Classified | Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	15,668,000		17,282,000
Classified | Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	74,075,000		76,099,000
Classified | Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	45,229,000		46,426,000
Classified | Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	28,846,000		29,673,000
Classified | Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	28,961,000		26,739,000
Classified | Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	117,000		694,000
Classified | Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	117,000		694,000
Classified | Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 3,601,000		$ 3,917,000