Loans, Allowance for Loan Losses, and Credit Quality (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2012
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	$ 297,409	$ 378,151
Provision for loan losses	4,000	3,000
Charge offs	(27,128)	(117,046)
Recoveries	12,642	33,304
Loans and Leases Receivable, Allowance, Ending Balance	286,923	297,409
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	14,480	16,787
Ending balance impaired loans collectively evaluated for impairment	43,160	52,504
Ending balance all other loans collectively evaluated for impairment	229,283	228,118
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	125,817	132,528
Ending balance impaired loans collectively evaluated for impairment	219,712	241,427
Ending balance all other loans collectively evaluated for impairment	15,206,033	15,037,067
Commercial and Industrial Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	97,852	124,374
Provision for loan losses	10,848	(1,645)
Charge offs	(7,075)	(43,240)
Recoveries	6,379	18,363
Loans and Leases Receivable, Allowance, Ending Balance	108,004	97,852
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	4,954	8,790
Ending balance impaired loans collectively evaluated for impairment	4,436	4,951
Ending balance all other loans collectively evaluated for impairment	98,614	84,111
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	22,583	27,213
Ending balance impaired loans collectively evaluated for impairment	39,910	40,109
Ending balance all other loans collectively evaluated for impairment	4,588,650	4,434,699
Commercial Real Estate Owner Occupied Portfolio [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	27,389	36,200
Provision for loan losses	(3,503)	(5,184)
Charge offs	(1,661)	(4,080)
Recoveries	143	453
Loans and Leases Receivable, Allowance, Ending Balance	22,368	27,389
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	819	654
Ending balance impaired loans collectively evaluated for impairment	2,739	3,157
Ending balance all other loans collectively evaluated for impairment	18,810	23,578
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	17,250	16,602
Ending balance impaired loans collectively evaluated for impairment	18,837	21,504
Ending balance all other loans collectively evaluated for impairment	1,163,426	1,181,641
Finance Leases Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	3,024	2,567
Provision for loan losses	(281)	(645)
Charge offs	0	(797)
Recoveries	12	1,899
Loans and Leases Receivable, Allowance, Ending Balance	2,755	3,024
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	4	0
Ending balance all other loans collectively evaluated for impairment	2,751	3,024
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	2,060	3,024
Ending balance impaired loans collectively evaluated for impairment	105	7
Ending balance all other loans collectively evaluated for impairment	55,743	61,165
Commercial Real Estate Investor Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	63,181	86,689
Provision for loan losses	3,178	(14,304)
Charge offs	(4,034)	(14,000)
Recoveries	3,871	4,796
Loans and Leases Receivable, Allowance, Ending Balance	66,196	63,181
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	6,196	5,241
Ending balance impaired loans collectively evaluated for impairment	3,795	4,446
Ending balance all other loans collectively evaluated for impairment	56,205	53,494
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	51,757	48,894
Ending balance impaired loans collectively evaluated for impairment	46,272	51,453
Ending balance all other loans collectively evaluated for impairment	2,802,138	2,806,412
Real Estate Construction Port Folio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	20,741	21,327
Provision for loan losses	3,898	873
Charge offs	(1,978)	(3,588)
Recoveries	586	2,129
Loans and Leases Receivable, Allowance, Ending Balance	23,247	20,741
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	482	1,079
Ending balance impaired loans collectively evaluated for impairment	2,888	2,332
Ending balance all other loans collectively evaluated for impairment	19,877	17,330
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	17,902	20,794
Ending balance impaired loans collectively evaluated for impairment	9,804	11,038
Ending balance all other loans collectively evaluated for impairment	701,439	623,549
Home Equity Port Folio Segments [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	56,826	70,144
Provision for loan losses	(11,826)	16,909
Charge offs	(7,230)	(34,125)
Recoveries	893	3,898
Loans and Leases Receivable, Allowance, Ending Balance	38,663	56,826
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,666	868
Ending balance impaired loans collectively evaluated for impairment	16,203	23,712
Ending balance all other loans collectively evaluated for impairment	20,794	32,246
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	3,598	4,671
Ending balance impaired loans collectively evaluated for impairment	39,903	44,512
Ending balance all other loans collectively evaluated for impairment	2,054,906	2,170,311
Installment Port Folio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	4,299	6,623
Provision for loan losses	(870)	(501)
Charge offs	(431)	(3,057)
Recoveries	254	1,234
Loans and Leases Receivable, Allowance, Ending Balance	3,252	4,299
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	790	1,155
Ending balance all other loans collectively evaluated for impairment	2,462	3,144
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	2,426	2,491
Ending balance all other loans collectively evaluated for impairment	445,019	464,236
Residential Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	24,097	30,227
Provision for loan losses	2,556	7,497
Charge offs	(4,719)	(14,159)
Recoveries	504	532
Loans and Leases Receivable, Allowance, Ending Balance	22,438	24,097
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	363	155
Ending balance impaired loans collectively evaluated for impairment	12,305	12,751
Ending balance all other loans collectively evaluated for impairment	9,770	11,191
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	10,667	11,330
Ending balance impaired loans collectively evaluated for impairment	62,455	70,313
Ending balance all other loans collectively evaluated for impairment	$ 3,394,712	$ 3,295,054

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Reflects the gross amount charged against earnings during the period as credit losses (bad debt expense) based on review of the loan and lease portfolio and application of the methodology for estimating credit losses.

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Reflects a reduction in bad debt expense attributable to collections of loans and lease receivables which had previously been fully or partially charged off as bad debts.

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Reflects the amount of loans and leases that have been removed, or charged off, from both loan receivables and the reserve for credit losses, typically because they are considered to be not salvageable or have been purchased by unconsolidated collection entities.

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A valuation allowance for financing receivables that are expected to be uncollectible.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

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