Loans (Allowance For Possible Loan Losses Disaggregated On Basis Of Impairment Methodology) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Industrial	$ 4,486,301	$ 3,916,867	$ 3,931,541
Commercial Real Estate	3,250,135	3,020,827	3,093,489
Consumer Real Estate	768,482	762,809	766,715
Consumer and Other	325,592	312,536	314,343
Unallocated	(19,470)	(17,910)	(16,511)
Total	8,811,040	7,995,129	8,089,577
Loans Individually Evaluated For Impairment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Industrial	161,577	189,139	235,143
Commercial Real Estate	170,077	241,451	273,289
Consumer Real Estate	894	2,470
Consumer and Other	420	554
Total	332,968	433,614	508,432
Loans Collectively Evaluated For Impairment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Industrial	4,324,724	3,727,728	3,696,398
Commercial Real Estate	3,080,058	2,779,376	2,820,200
Consumer Real Estate	767,588	760,339	766,715
Consumer and Other	325,172	311,982	314,343
Unallocated	(19,470)	(17,910)	(16,511)
Total	8,478,072	7,561,515	7,581,145
Allowance For Loan And Lease Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Industrial	51,542	42,774	46,885
Commercial Real Estate	27,641	20,912	20,812
Consumer Real Estate	5,394	3,540	3,446
Consumer and Other	3,902	12,635	12,807
Unallocated	16,922	30,286	31,483
Total	105,401	110,147	115,433
Allowance For Loan And Lease Losses [Member] \| Loans Individually Evaluated For Impairment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Industrial	14,301	15,829	23,263
Commercial Real Estate	2,149	3,625	4,075
Consumer Real Estate		95
Total	16,450	19,549	27,338
Allowance For Loan And Lease Losses [Member] \| Loans Collectively Evaluated For Impairment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Industrial	37,241	26,945	23,622
Commercial Real Estate	25,492	17,287	16,737
Consumer Real Estate	5,394	3,445	3,446
Consumer and Other	3,902	12,635	12,807
Unallocated	16,922	30,286	31,483
Total	$ 88,951	$ 90,598	$ 88,095

Amount before allowance of other consumer installment loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of consumer real estate loans. Includes, but not limited to, construction financing, residential mortgage loans, and home equity lines of credit. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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- Definition

Amount before allowance of loans issued to commercial and industrial institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes real estate loans and loans covered under loss sharing agreements.

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- Definition

Amount before allowance of commercial loans issued to businesses to acquire, develop, construct, improve, or refinance land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph a

-Article 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5066-111524

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-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 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

-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 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Paragraph 51, 52, 53

-IssueDate 2006-05-01

-Chapter 8

-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.

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