Loans, Allowance for Loan Losses, and Credit Quality (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2012	Dec. 31, 2011
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	$ 378,151	$ 476,813
Provision for loan losses	0	52,000
Charge offs	(31,259)	(189,732)
Recoveries	9,406	39,070
Loans and Leases Receivable, Allowance, Ending Balance	356,298	378,151
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	29,314	36,809
Ending balance impaired loans collectively evaluated for impairment	71,929	67,970
Ending balance all other loans collectively evaluated for impairment	255,055	273,372
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	186,584	215,478
Ending balance impaired loans collectively evaluated for impairment	261,220	254,458
Ending balance all other loans collectively evaluated for impairment	13,805,921	13,561,135
Commercial Portfolio Segment
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	124,374	137,770
Provision for loan losses	(1,658)	8,916
Charge offs	(8,035)	(38,662)
Recoveries	4,163	16,350
Loans and Leases Receivable, Allowance, Ending Balance	118,844	124,374
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	9,039	7,619
Ending balance impaired loans collectively evaluated for impairment	8,104	7,688
Ending balance all other loans collectively evaluated for impairment	101,701	109,067
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	35,910	41,474
Ending balance impaired loans collectively evaluated for impairment	40,353	37,153
Ending balance all other loans collectively evaluated for impairment	3,642,753	3,646,109
Commercial Real Estate Owner Occupied Portfolio Segment
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	36,200	54,320
Provision for loan losses	(2,594)	(11,144)
Charge offs	(732)	(9,485)
Recoveries	317	2,509
Loans and Leases Receivable, Allowance, Ending Balance	33,191	36,200
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	2,701	3,608
Ending balance impaired loans collectively evaluated for impairment	4,765	3,962
Ending balance all other loans collectively evaluated for impairment	25,725	28,630
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	21,489	26,049
Ending balance impaired loans collectively evaluated for impairment	17,325	17,807
Ending balance all other loans collectively evaluated for impairment	1,035,941	1,042,973
Finance Leases Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	2,567	7,396
Provision for loan losses	(1,647)	(6,611)
Charge offs	0	(173)
Recoveries	1,836	1,955
Loans and Leases Receivable, Allowance, Ending Balance	2,756	2,567
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	133	161
Ending balance impaired loans collectively evaluated for impairment	24	34
Ending balance all other loans collectively evaluated for impairment	2,599	2,372
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	8,428	9,792
Ending balance impaired loans collectively evaluated for impairment	612	852
Ending balance all other loans collectively evaluated for impairment	52,168	47,550
Commercial Real Estate Investor Portfolio Segment
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	86,689	111,264
Provision for loan losses	(762)	(762)
Charge offs	(8,393)	(29,479)
Recoveries	1,039	5,666
Loans and Leases Receivable, Allowance, Ending Balance	78,573	86,689
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	11,599	16,623
Ending balance impaired loans collectively evaluated for impairment	9,712	8,378
Ending balance all other loans collectively evaluated for impairment	57,262	61,688
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	75,874	85,287
Ending balance impaired loans collectively evaluated for impairment	59,001	57,482
Ending balance all other loans collectively evaluated for impairment	2,529,376	2,420,998
Real Estate Construction Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	21,327	56,772
Provision for loan losses	(2,320)	(4,744)
Charge offs	(924)	(38,222)
Recoveries	694	7,521
Loans and Leases Receivable, Allowance, Ending Balance	18,777	21,327
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	2,904	4,919
Ending balance impaired loans collectively evaluated for impairment	4,696	4,266
Ending balance all other loans collectively evaluated for impairment	11,177	12,142
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	27,474	31,933
Ending balance impaired loans collectively evaluated for impairment	20,767	20,850
Ending balance all other loans collectively evaluated for impairment	517,712	531,263
Home Equity Portfolio Segments
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	70,144	55,090
Provision for loan losses	4,230	54,476
Charge offs	(9,761)	(42,623)
Recoveries	811	3,201
Loans and Leases Receivable, Allowance, Ending Balance	65,424	70,144
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,763	2,922
Ending balance impaired loans collectively evaluated for impairment	27,196	27,914
Ending balance all other loans collectively evaluated for impairment	36,465	39,308
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	7,817	9,542
Ending balance impaired loans collectively evaluated for impairment	45,903	46,315
Ending balance all other loans collectively evaluated for impairment	2,448,050	2,448,847
Installment Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	6,623	17,328
Provision for loan losses	162	3,845
Charge offs	(604)	(16,134)
Recoveries	503	1,584
Loans and Leases Receivable, Allowance, Ending Balance	6,684	6,623
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	2,004	2,021
Ending balance all other loans collectively evaluated for impairment	4,680	4,602
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	3,626	3,730
Ending balance all other loans collectively evaluated for impairment	534,002	554,052
Residential Portfolio Segment
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	30,227	36,873
Provision for loan losses	4,589	8,024
Charge offs	(2,810)	(14,954)
Recoveries	43	284
Loans and Leases Receivable, Allowance, Ending Balance	32,049	30,227
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,175	957
Ending balance impaired loans collectively evaluated for impairment	15,428	13,707
Ending balance all other loans collectively evaluated for impairment	15,446	15,563
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	9,592	11,401
Ending balance impaired loans collectively evaluated for impairment	73,633	70,269
Ending balance all other loans collectively evaluated for impairment	$ 3,045,919	$ 2,869,343

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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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The amount of the recorded 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, accounts receivable (with terms exceeding one year), notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets.

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-Publisher FASB

-Name Accounting Standards Codification

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

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-Topic 310

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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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The 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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- Definition

The allowance for loan and lease losses represents the reserve to cover probable credit losses related to specifically identified loans and leases, as well as probable credit losses inherent in the remainder of the loan portfolio as of the balance sheet date. For banks, include currently required allocated transfer risk reserves. Include carryover of or adjustments to the allowance for loan losses in connection with business combinations determined to be appropriate.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Paragraph 8

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-Subsection I

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-Subsection 1

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

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