Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Allowance for Loan and Lease Losses
Beginning Balance	$ 262,557,000	$ 257,007,000
Provision for credit losses, net of transfers	8,260,000	10,932,000
Charge-offs	(40,513,000)	(48,205,000)
Recoveries	47,584,000	42,823,000
Net (charge-offs) recoveries	7,071,000	(5,382,000)
Ending Balance	277,888,000	262,557,000
Allowance individually evaluated for impairment	2,403,000	13,262,000
Allowance collectively evaluated for impairment	275,485,000	249,295,000
Loans and leases, excluding covered loans	14,818,295,000	12,309,385,000
Loans and leases, individually evaluated for impairment	138,592,000	148,734,000
Loans and leases, collectively evaluated for impairment	14,679,703,000	12,160,651,000
Provision for credit losses in the allowance	10,000,000	12,500,000
Transfers to or from reserve for off-balance sheet credit commitments	1,700,000	1,600,000
Reserve for Off Balance Sheet Credit Commitments
Balance, beginning of period	23,097,000	21,529,000
Transfers from allowance for loan and lease losses	1,740,000	1,568,000
Balance, end of period	24,837,000	23,097,000
Commercial (includes lease financing)
Allowance for Loan and Lease Losses
Beginning Balance	82,965,000	82,451,000
Provision for credit losses, net of transfers	10,750,000	15,284,000
Charge-offs	(24,407,000)	(30,512,000)
Recoveries	34,848,000	15,742,000
Net (charge-offs) recoveries	10,441,000	(14,770,000)
Ending Balance	104,156,000	82,965,000
Allowance individually evaluated for impairment	952,000	7,135,000
Allowance collectively evaluated for impairment	103,204,000	75,830,000
Loans and leases, excluding covered loans	6,949,073,000	5,246,081,000
Loans and leases, individually evaluated for impairment	26,277,000	25,808,000
Loans and leases, collectively evaluated for impairment	6,922,796,000	5,220,273,000
Commercial real estate mortgages
Allowance for Loan and Lease Losses
Beginning Balance	45,967,000	52,516,000
Provision for credit losses, net of transfers	2,357,000	(13,491,000)
Charge-offs	(1,611,000)	(4,573,000)
Recoveries	1,527,000	11,515,000
Net (charge-offs) recoveries	(84,000)	6,942,000
Ending Balance	48,240,000	45,967,000
Allowance individually evaluated for impairment	1,326,000	1,551,000
Allowance collectively evaluated for impairment	46,914,000	44,416,000
Loans and leases, excluding covered loans	2,829,694,000	2,110,749,000
Loans and leases, individually evaluated for impairment	53,085,000	30,678,000
Loans and leases, collectively evaluated for impairment	2,776,609,000	2,080,071,000
Residential mortgage
Allowance for Loan and Lease Losses
Beginning Balance	14,029,000	16,753,000
Provision for credit losses, net of transfers	(1,951,000)	(1,641,000)
Charge-offs	(2,402,000)	(1,475,000)
Recoveries	823,000	392,000
Net (charge-offs) recoveries	(1,579,000)	(1,083,000)
Ending Balance	10,499,000	14,029,000
Allowance individually evaluated for impairment	9,000	108,000
Allowance collectively evaluated for impairment	10,490,000	13,921,000
Loans and leases, excluding covered loans	3,962,205,000	3,763,218,000
Loans and leases, individually evaluated for impairment	8,810,000	9,146,000
Loans and leases, collectively evaluated for impairment	3,953,395,000	3,754,072,000
Real estate construction
Allowance for Loan and Lease Losses
Beginning Balance	23,347,000	40,824,000
Provision for credit losses, net of transfers	(8,757,000)	(22,507,000)
Charge-offs	(9,769,000)	(8,897,000)
Recoveries	8,309,000	13,927,000
Net (charge-offs) recoveries	(1,460,000)	5,030,000
Ending Balance	13,130,000	23,347,000
Allowance individually evaluated for impairment		4,377,000
Allowance collectively evaluated for impairment	13,130,000	18,970,000
Loans and leases, excluding covered loans	222,780,000	315,609,000
Loans and leases, individually evaluated for impairment	45,510,000	75,811,000
Loans and leases, collectively evaluated for impairment	177,270,000	239,798,000
Equity lines of credit
Allowance for Loan and Lease Losses
Beginning Balance	8,024,000	7,229,000
Provision for credit losses, net of transfers	382,000	2,561,000
Charge-offs	(1,258,000)	(1,834,000)
Recoveries	95,000	68,000
Net (charge-offs) recoveries	(1,163,000)	(1,766,000)
Ending Balance	7,243,000	8,024,000
Allowance individually evaluated for impairment	116,000	91,000
Allowance collectively evaluated for impairment	7,127,000	7,933,000
Loans and leases, excluding covered loans	711,750,000	741,081,000
Loans and leases, individually evaluated for impairment	4,461,000	6,633,000
Loans and leases, collectively evaluated for impairment	707,289,000	734,448,000
Installment loan
Allowance for Loan and Lease Losses
Beginning Balance	1,959,000	3,931,000
Provision for credit losses, net of transfers	(1,028,000)	(2,237,000)
Charge-offs	(1,066,000)	(914,000)
Recoveries	1,982,000	1,179,000
Net (charge-offs) recoveries	916,000	265,000
Ending Balance	1,847,000	1,959,000
Allowance collectively evaluated for impairment	1,847,000	1,959,000
Loans and leases, excluding covered loans	142,793,000	132,647,000
Loans and leases, individually evaluated for impairment	449,000	658,000
Loans and leases, collectively evaluated for impairment	142,344,000	131,989,000
Unallocated
Allowance for Loan and Lease Losses
Beginning Balance	86,266,000	53,303,000
Provision for credit losses, net of transfers	6,507,000	32,963,000
Ending Balance	92,773,000	86,266,000
Allowance collectively evaluated for impairment	$ 92,773,000	$ 86,266,000