Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 9) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 16,566,133,000	$ 13,724,651,000	$ 16,566,133,000	$ 13,724,651,000	$ 14,818,295,000
Covered Loans Allowance
Balance, beginning of period	24,414,000	43,147,000	44,781,000	64,565,000
Provision for losses	2,496,000	18,089,000	461,000	38,848,000
Reduction in allowance due to loan removals	(1,028,000)	(16,258,000)	(19,360,000)	(58,435,000)
Balance, end of period	25,882,000	44,978,000	25,882,000	44,978,000
Loans on nonaccrual status	69,602,000		69,602,000		99,787,000
Loans 90 days or more past due on accrual status	383,000		383,000		981,000
Covered loans
Covered Loans Allowance
Loans on nonaccrual status	0		0		0
Covered loans 30 to 89 days delinquent	6,400,000		6,400,000		43,400,000
Loans 90 days or more past due on accrual status	63,100,000		63,100,000		112,400,000
Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	7,126,158,000		7,126,158,000		6,211,353,000
Covered Loans Allowance
Loans on nonaccrual status	10,073,000		10,073,000		9,087,000
Loans 90 days or more past due on accrual status	3,000		3,000		602,000
Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,077,183,000	2,436,218,000	3,077,183,000	2,436,218,000	2,739,284,000
Covered Loans Allowance
Loans on nonaccrual status	19,020,000		19,020,000		33,198,000
Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	4,418,231,000	3,897,690,000	4,418,231,000	3,897,690,000	3,962,205,000
Covered Loans Allowance
Loans on nonaccrual status	9,674,000		9,674,000		9,603,000
Loans 90 days or more past due on accrual status	379,000		379,000		379,000
Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,463,384,000		1,463,384,000		1,465,474,000
Covered Loans Allowance
Loans on nonaccrual status	3,901,000		3,901,000		4,902,000
Loans 90 days or more past due on accrual status	379,000		379,000		379,000
Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,954,847,000		2,954,847,000		2,496,731,000
Covered Loans Allowance
Loans on nonaccrual status	5,773,000		5,773,000		4,701,000
Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	380,489,000	269,583,000	380,489,000	269,583,000	313,190,000
Covered Loans Allowance
Loans on nonaccrual status	25,471,000		25,471,000		40,882,000
Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	350,691,000		350,691,000		254,807,000
Covered Loans Allowance
Loans on nonaccrual status	11,553,000		11,553,000		15,067,000
Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	29,798,000		29,798,000		58,383,000
Covered Loans Allowance
Loans on nonaccrual status	13,918,000		13,918,000		25,815,000
Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	681,879,000	718,966,000	681,879,000	718,966,000	711,750,000
Covered Loans Allowance
Loans on nonaccrual status	5,289,000		5,289,000		6,424,000
Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	152,107,000	137,632,000	152,107,000	137,632,000	142,793,000
Covered Loans Allowance
Loans on nonaccrual status	21,000		21,000		473,000
Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	379,000		379,000		437,000
Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	151,728,000		151,728,000		142,356,000
Covered Loans Allowance
Loans on nonaccrual status	21,000		21,000		473,000
Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	730,086,000		730,086,000		737,720,000
Covered Loans Allowance
Loans on nonaccrual status	54,000		54,000		120,000
Loans 90 days or more past due on accrual status	1,000		1,000
Nonclassified
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	16,221,212,000		16,221,212,000		14,415,241,000
Nonclassified | Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	7,011,906,000		7,011,906,000		6,073,459,000
Nonclassified | Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,961,319,000		2,961,319,000		2,597,863,000
Nonclassified | Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	4,374,892,000		4,374,892,000		3,928,719,000
Nonclassified | Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,443,459,000		1,443,459,000		1,449,270,000
Nonclassified | Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	2,931,433,000		2,931,433,000		2,479,449,000
Nonclassified | Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	340,497,000		340,497,000		254,287,000
Nonclassified | Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	324,908,000		324,908,000		225,577,000
Nonclassified | Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	15,589,000		15,589,000		28,710,000
Nonclassified | Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	653,349,000		653,349,000		685,011,000
Nonclassified | Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	151,749,000		151,749,000		142,099,000
Nonclassified | Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	379,000		379,000		437,000
Nonclassified | Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	151,370,000		151,370,000		141,662,000
Nonclassified | Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	727,500,000		727,500,000		733,803,000
Classified
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	344,921,000		344,921,000		403,054,000
Classified | Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	114,252,000		114,252,000		137,894,000
Classified | Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	115,864,000		115,864,000		141,421,000
Classified | Residential mortgage
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	43,339,000		43,339,000		33,486,000
Classified | Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	19,925,000		19,925,000		16,204,000
Classified | Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	23,414,000		23,414,000		17,282,000
Classified | Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	39,992,000		39,992,000		58,903,000
Classified | Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	25,783,000		25,783,000		29,230,000
Classified | Land
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	14,209,000		14,209,000		29,673,000
Classified | Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	28,530,000		28,530,000		26,739,000
Classified | Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	358,000		358,000		694,000
Classified | Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	358,000		358,000		694,000
Classified | Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 2,586,000		$ 2,586,000		$ 3,917,000