Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Allowance for Loan and Lease Losses
Beginning Balance	$ 277,888,000	$ 262,557,000
Provision (reduction) for credit losses, net of transfers	(9,107,000)	8,260,000
Charge-offs	(10,467,000)	(40,513,000)
Recoveries	44,270,000	47,584,000
Net recoveries (charge-offs)	33,803,000	7,071,000
Ending Balance	302,584,000	277,888,000
Allowance individually evaluated for impairment	3,025,000	2,403,000
Allowance collectively evaluated for impairment	299,559,000	275,485,000
Loans and leases, excluding covered loans	17,170,438,000	14,818,295,000
Loans and leases, individually evaluated for impairment	100,664,000	138,592,000
Loans and leases, collectively evaluated for impairment	17,069,774,000	14,679,703,000
Provision for credit losses in the allowance		10,000,000
Transfers to or from reserve for off-balance sheet credit commitments	9,100,000	1,700,000
Reserve for Off Balance Sheet Credit Commitments
Balance, beginning of the year	24,837,000	23,097,000
Transfers from allowance for loan and lease losses	9,107,000	1,740,000
Balance, end of the year	33,944,000	24,837,000
Commercial (includes lease financing)
Allowance for Loan and Lease Losses
Beginning Balance	104,731,000	83,514,000
Provision (reduction) for credit losses, net of transfers	(6,546,000)	10,776,000
Charge-offs	(8,072,000)	(24,407,000)
Recoveries	26,990,000	34,848,000
Net recoveries (charge-offs)	18,918,000	10,441,000
Ending Balance	117,103,000	104,731,000
Allowance individually evaluated for impairment	1,961,000	952,000
Allowance collectively evaluated for impairment	115,142,000	103,779,000
Loans and leases, excluding covered loans	8,164,823,000	6,949,073,000
Loans and leases, individually evaluated for impairment	31,857,000	26,277,000
Loans and leases, collectively evaluated for impairment	8,132,966,000	6,922,796,000
Commercial real estate mortgages
Allowance for Loan and Lease Losses
Beginning Balance	48,901,000	48,451,000
Provision (reduction) for credit losses, net of transfers	1,301,000	534,000
Charge-offs	(1,315,000)	(1,611,000)
Recoveries	1,791,000	1,527,000
Net recoveries (charge-offs)	476,000	(84,000)
Ending Balance	50,678,000	48,901,000
Allowance individually evaluated for impairment	586,000	1,326,000
Allowance collectively evaluated for impairment	50,092,000	47,575,000
Loans and leases, excluding covered loans	3,223,001,000	2,739,284,000
Loans and leases, individually evaluated for impairment	38,154,000	53,085,000
Loans and leases, collectively evaluated for impairment	3,184,847,000	2,686,199,000
Residential mortgage
Allowance for Loan and Lease Losses
Beginning Balance	10,558,000	14,122,000
Provision (reduction) for credit losses, net of transfers	941,000	(1,985,000)
Charge-offs	(106,000)	(2,402,000)
Recoveries	147,000	823,000
Net recoveries (charge-offs)	41,000	(1,579,000)
Ending Balance	11,540,000	10,558,000
Allowance individually evaluated for impairment	478,000	9,000
Allowance collectively evaluated for impairment	11,062,000	10,549,000
Loans and leases, excluding covered loans	4,554,311,000	3,962,205,000
Loans and leases, individually evaluated for impairment	9,211,000	8,810,000
Loans and leases, collectively evaluated for impairment	4,545,100,000	3,953,395,000
Real estate construction
Allowance for Loan and Lease Losses
Beginning Balance	11,784,000	20,155,000
Provision (reduction) for credit losses, net of transfers	(18,386,000)	(6,911,000)
Charge-offs	(100,000)	(9,769,000)
Recoveries	13,053,000	8,309,000
Net recoveries (charge-offs)	12,953,000	(1,460,000)
Ending Balance	6,351,000	11,784,000
Allowance collectively evaluated for impairment	6,351,000	11,784,000
Loans and leases, excluding covered loans	367,004,000	313,190,000
Loans and leases, individually evaluated for impairment	19,097,000	45,510,000
Loans and leases, collectively evaluated for impairment	347,907,000	267,680,000
Home Equity Loans and Lines of Credit
Allowance for Loan and Lease Losses
Beginning Balance	7,283,000	8,077,000
Provision (reduction) for credit losses, net of transfers	(804,000)	369,000
Charge-offs	(500,000)	(1,258,000)
Recoveries	698,000	95,000
Net recoveries (charge-offs)	198,000	(1,163,000)
Ending Balance	6,677,000	7,283,000
Allowance individually evaluated for impairment		116,000
Allowance collectively evaluated for impairment	6,677,000	7,167,000
Loans and leases, excluding covered loans	709,344,000	711,750,000
Loans and leases, individually evaluated for impairment	2,329,000	4,461,000
Loans and leases, collectively evaluated for impairment	707,015,000	707,289,000
Installment
Allowance for Loan and Lease Losses
Beginning Balance	1,858,000	1,972,000
Provision (reduction) for credit losses, net of transfers	(1,233,000)	(1,030,000)
Charge-offs	(374,000)	(1,066,000)
Recoveries	1,591,000	1,982,000
Net recoveries (charge-offs)	1,217,000	916,000
Ending Balance	1,842,000	1,858,000
Allowance collectively evaluated for impairment	1,842,000	1,858,000
Loans and leases, excluding covered loans	151,955,000	142,793,000
Loans and leases, individually evaluated for impairment	16,000	449,000
Loans and leases, collectively evaluated for impairment	151,939,000	142,344,000
Unallocated
Allowance for Loan and Lease Losses
Beginning Balance	92,773,000	86,266,000
Provision (reduction) for credit losses, net of transfers	15,620,000	6,507,000
Ending Balance	108,393,000	92,773,000
Allowance collectively evaluated for impairment	$ 108,393,000	$ 92,773,000