Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 9) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 17,170,438,000	$ 14,818,295,000
Covered Loans Allowance
Balance, beginning of period	44,781,000	64,565,000
Provision for losses	635,000	45,346,000	43,646,000
Net recoveries	9,000
Reduction in allowance due to loan removals	(29,503,000)	(65,130,000)
Balance, end of period	15,922,000	44,781,000	64,565,000
Loans on nonaccrual status	68,651,000	99,787,000
Loans 90 days or more past due on accrual status	453,000	981,000
Covered loans
Covered Loans Allowance
Loans on nonaccrual status	0	0
Covered loans 30 to 89 days delinquent	15,500,000	43,400,000
Loans 90 days or more past due on accrual status	45,700,000	112,400,000
Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	7,404,116,000	6,211,353,000
Covered Loans Allowance
Loans on nonaccrual status	14,248,000	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	3,223,001,000	2,739,284,000
Covered Loans Allowance
Loans on nonaccrual status	18,449,000	33,198,000
Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	4,554,311,000	3,962,205,000
Covered Loans Allowance
Loans on nonaccrual status	11,661,000	9,603,000
Loans 90 days or more past due on accrual status	379,000	379,000
Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,440,451,000	1,465,474,000
Covered Loans Allowance
Loans on nonaccrual status	3,789,000	4,902,000
Loans 90 days or more past due on accrual status	379,000	379,000
Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,113,860,000	2,496,731,000
Covered Loans Allowance
Loans on nonaccrual status	7,872,000	4,701,000
Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	367,004,000	313,190,000
Covered Loans Allowance
Loans on nonaccrual status	19,067,000	40,882,000
Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	337,598,000	254,807,000
Covered Loans Allowance
Loans on nonaccrual status	5,467,000	15,067,000
Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	29,406,000	58,383,000
Covered Loans Allowance
Loans on nonaccrual status	13,600,000	25,815,000
Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	709,344,000	711,750,000
Covered Loans Allowance
Loans on nonaccrual status	5,144,000	6,424,000
Loans 90 days or more past due on accrual status	74,000
Installment
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	151,955,000	142,793,000
Covered Loans Allowance
Loans on nonaccrual status	32,000	473,000
Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	362,000	437,000
Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	151,593,000	142,356,000
Covered Loans Allowance
Loans on nonaccrual status	32,000	473,000
Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	760,707,000	737,720,000
Covered Loans Allowance
Loans on nonaccrual status	50,000	120,000
Nonclassified
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	16,854,953,000	14,415,241,000
Nonclassified | Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	7,258,303,000	6,073,459,000
Nonclassified | Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,139,707,000	2,597,863,000
Nonclassified | Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	4,512,723,000	3,928,719,000
Nonclassified | Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,425,087,000	1,449,270,000
Nonclassified | Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,087,636,000	2,479,449,000
Nonclassified | Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	347,653,000	254,287,000
Nonclassified | Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	332,131,000	225,577,000
Nonclassified | Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	15,522,000	28,710,000
Nonclassified | Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	687,732,000	685,011,000
Nonclassified | Installment
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	151,830,000	142,099,000
Nonclassified | Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	362,000	437,000
Nonclassified | Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	151,468,000	141,662,000
Nonclassified | Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	757,005,000	733,803,000
Classified
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	315,485,000	403,054,000
Classified | Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	145,813,000	137,894,000
Classified | Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	83,294,000	141,421,000
Classified | Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	41,588,000	33,486,000
Classified | Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	15,364,000	16,204,000
Classified | Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	26,224,000	17,282,000
Classified | Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	19,351,000	58,903,000
Classified | Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	5,467,000	29,230,000
Classified | Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	13,884,000	29,673,000
Classified | Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	21,612,000	26,739,000
Classified | Installment
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	125,000	694,000
Classified | Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	125,000	694,000
Classified | Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 3,702,000	$ 3,917,000