Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for Loan and Lease Losses
Beginning Balance	$ 257,007,000	$ 288,493,000
Provision for credit losses, net of transfers	10,932,000	98,811,000
Charge-offs	(48,205,000)	(143,256,000)
Recoveries	42,823,000	12,959,000
Net (charge-offs) recoveries	(5,382,000)	(130,297,000)
Ending Balance	262,557,000	257,007,000	288,493,000
Allowance individually evaluated for impairment	13,262,000	5,444,000
Allowance collectively evaluated for impairment	249,295,000	251,563,000
Loans and leases, excluding covered loans	12,309,385,000	11,386,628,000
Loans and leases, individually evaluated for impairment	148,520,000	190,412,000
Loans and leases, collectively evaluated for impairment	12,160,865,000	11,196,216,000
Provision for credit losses on loans and leases, excluding covered loans	12,500,000	103,000,000	285,000,000
Transfers to reserve for off-balance sheet credit commitments	1,600,000	4,200,000
Reserve for Off Balance Sheet Credit Commitments
Balance, beginning of period	21,529,000	17,340,000	22,703,000
Transfers from (to) allowance for loan and lease losses	1,568,000	4,189,000	(5,363,000)
Balance, end of period	23,097,000	21,529,000	17,340,000
Commercial (includes lease financing)
Allowance for Loan and Lease Losses
Beginning Balance	82,451,000	110,547,000
Provision for credit losses, net of transfers	15,284,000	35,200,000
Charge-offs	(30,512,000)	(69,427,000)
Recoveries	15,742,000	6,131,000
Net (charge-offs) recoveries	(14,770,000)	(63,296,000)
Ending Balance	82,965,000	82,451,000
Allowance individually evaluated for impairment	7,135,000	2,592,000
Allowance collectively evaluated for impairment	75,830,000	79,859,000
Loans and leases, excluding covered loans	5,246,081,000	4,514,329,000
Loans and leases, individually evaluated for impairment	25,719,000	16,715,000
Loans and leases, collectively evaluated for impairment	5,220,362,000	4,497,614,000
Commercial real estate mortgages
Allowance for Loan and Lease Losses
Beginning Balance	52,516,000	52,011,000
Provision for credit losses, net of transfers	(13,491,000)	30,103,000
Charge-offs	(4,573,000)	(29,833,000)
Recoveries	11,515,000	235,000
Net (charge-offs) recoveries	6,942,000	(29,598,000)
Ending Balance	45,967,000	52,516,000
Allowance individually evaluated for impairment	1,551,000	1,889,000
Allowance collectively evaluated for impairment	44,416,000	50,627,000
Loans and leases, excluding covered loans	2,110,749,000	1,958,317,000
Loans and leases, individually evaluated for impairment	30,630,000	42,580,000
Loans and leases, collectively evaluated for impairment	2,080,119,000	1,915,737,000
Residential mortgage
Allowance for Loan and Lease Losses
Beginning Balance	16,753,000	12,797,000
Provision for credit losses, net of transfers	(1,641,000)	7,153,000
Charge-offs	(1,475,000)	(3,327,000)
Recoveries	392,000	130,000
Net (charge-offs) recoveries	(1,083,000)	(3,197,000)
Ending Balance	14,029,000	16,753,000
Allowance individually evaluated for impairment	108,000	342,000
Allowance collectively evaluated for impairment	13,921,000	16,411,000
Loans and leases, excluding covered loans	3,763,218,000	3,552,312,000
Loans and leases, individually evaluated for impairment	9,116,000	16,889,000
Loans and leases, collectively evaluated for impairment	3,754,102,000	3,535,424,000
Real estate construction
Allowance for Loan and Lease Losses
Beginning Balance	40,824,000	53,722,000
Provision for credit losses, net of transfers	(22,507,000)	17,686,000
Charge-offs	(8,897,000)	(36,020,000)
Recoveries	13,927,000	5,436,000
Net (charge-offs) recoveries	5,030,000	(30,584,000)
Ending Balance	23,347,000	40,824,000
Allowance individually evaluated for impairment	4,377,000	366,000
Allowance collectively evaluated for impairment	18,970,000	40,458,000
Loans and leases, excluding covered loans	315,609,000	467,785,000
Loans and leases, individually evaluated for impairment	75,798,000	108,221,000
Loans and leases, collectively evaluated for impairment	239,811,000	359,564,000
Equity lines of credit
Allowance for Loan and Lease Losses
Beginning Balance	7,229,000	3,734,000
Provision for credit losses, net of transfers	2,561,000	5,463,000
Charge-offs	(1,834,000)	(2,120,000)
Recoveries	68,000	152,000
Net (charge-offs) recoveries	(1,766,000)	(1,968,000)
Ending Balance	8,024,000	7,229,000
Allowance individually evaluated for impairment	91,000	255,000
Allowance collectively evaluated for impairment	7,933,000	6,974,000
Loans and leases, excluding covered loans	741,081,000	733,741,000
Loans and leases, individually evaluated for impairment	609,000	4,859,000
Loans and leases, collectively evaluated for impairment	734,472,000	728,882,000
Installment loan
Allowance for Loan and Lease Losses
Beginning Balance	3,931,000	4,665,000
Provision for credit losses, net of transfers	(2,237,000)	920,000
Charge-offs	(914,000)	(2,529,000)
Recoveries	1,179,000	875,000
Net (charge-offs) recoveries	265,000	(1,654,000)
Ending Balance	1,959,000	3,931,000
Allowance collectively evaluated for impairment	1,959,000	3,931,000
Loans and leases, excluding covered loans	132,647,000	160,144,000
Loans and leases, individually evaluated for impairment	648,000	1,148,000
Loans and leases, collectively evaluated for impairment	131,999,000	158,996,000
Unallocated
Allowance for Loan and Lease Losses
Beginning Balance	53,303,000	51,017,000
Provision for credit losses, net of transfers	32,963,000	2,286,000
Ending Balance	86,266,000	53,303,000
Allowance collectively evaluated for impairment	$ 86,266,000	$ 53,303,000