Loans (Unallocated Portion of Allowance for Loan Losses) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	$ 92,438	$ 104,453	$ 110,147	$ 126,316
Historical Valuation Allowances [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	53,738	56,609
Specific Valuation Allowances [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	6,926	8,237
Environmental Risk Adjustment [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	11,806	12,775
Distressed Industries [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	8,196	7,065
Excessive Industry Concentrations [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	1,866	7,086
Large Relationship Concentrations [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,610	2,401
Highly-Leveraged Credit Relationships [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	5,154	3,604
Policy Exceptions [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,492	2,466
Credit and Collateral Exceptions [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	1,398	1,635
Loans Not Reviewed by Concurrence [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	7,524	8,260
Adjustment for Recoveries [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	(12,200)	(13,768)
General Macroeconomic Risk [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,928	8,083
Commercial and Industrial [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	52,790	54,164	42,774	57,789
Commercial and Industrial [Member] | Historical Valuation Allowances [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	29,357	30,565
Commercial and Industrial [Member] | Specific Valuation Allowances [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	4,140	5,100
Commercial and Industrial [Member] | Environmental Risk Adjustment [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	5,497	6,593
Commercial and Industrial [Member] | Distressed Industries [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	7,812	5,883
Commercial and Industrial [Member] | Excessive Industry Concentrations [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	1,499	4,291
Commercial and Industrial [Member] | Large Relationship Concentrations [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	1,529	1,420
Commercial and Industrial [Member] | Highly-Leveraged Credit Relationships [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	4,535	2,905
Commercial and Industrial [Member] | Loans Not Reviewed by Concurrence [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,009	2,277
Commercial and Industrial [Member] | Adjustment for Recoveries [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	(3,588)	(4,870)
Commercial Real Estate [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	22,590	29,346	20,912	28,534
Commercial Real Estate [Member] | Historical Valuation Allowances [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	13,042	15,687
Commercial Real Estate [Member] | Specific Valuation Allowances [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,786	3,137
Commercial Real Estate [Member] | Environmental Risk Adjustment [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	3,314	3,682
Commercial Real Estate [Member] | Distressed Industries [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	384	1,182
Commercial Real Estate [Member] | Excessive Industry Concentrations [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	367	2,795
Commercial Real Estate [Member] | Large Relationship Concentrations [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	1,081	981
Commercial Real Estate [Member] | Highly-Leveraged Credit Relationships [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	619	699
Commercial Real Estate [Member] | Loans Not Reviewed by Concurrence [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,201	2,413
Commercial Real Estate [Member] | Adjustment for Recoveries [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	(1,204)	(1,230)
Consumer Real Estate [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	5,230	5,252	3,540	3,223
Consumer Real Estate [Member] | Historical Valuation Allowances [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,644	3,013
Consumer Real Estate [Member] | Environmental Risk Adjustment [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	664	684
Consumer Real Estate [Member] | Loans Not Reviewed by Concurrence [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,250	2,411
Consumer Real Estate [Member] | Adjustment for Recoveries [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	(328)	(856)
Consumer and Other [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	5,010	3,507	12,635	11,974
Consumer and Other [Member] | Historical Valuation Allowances [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	8,695	7,344
Consumer and Other [Member] | Environmental Risk Adjustment [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,331	1,816
Consumer and Other [Member] | Loans Not Reviewed by Concurrence [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	1,064	1,159
Consumer and Other [Member] | Adjustment for Recoveries [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	(7,080)	(6,812)
Unallocated [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	6,818	12,184	30,286	24,796
Unallocated [Member] | Policy Exceptions [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	2,492	2,466
Unallocated [Member] | Credit and Collateral Exceptions [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	1,398	1,635
Unallocated [Member] | General Macroeconomic Risk [Member]
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Portion of allowance for loan losses	$ 2,928	$ 8,083