Loans and Leases (Credit Quality Indicators Credit Exposure) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	$ 12,675,607		$ 10,447,930		$ 9,702,669
Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	7,844,304		6,384,511
Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	4,831,303		4,063,419
Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	6,887,480	[1]	5,637,216	[1]
Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	415,387	[2]	343,989	[2]
Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	541,437	[3]	403,306	[3]
Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	4,792,413		4,027,704
Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	38,890	[4]	35,715	[4]
Legacy Loans And Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	10,399,602		9,833,296
Legacy Loans And Leases [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	6,259,895		6,138,987
Legacy Loans And Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	4,139,706		3,694,309
Legacy Loans And Leases [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	5,665,819	[1]	5,510,021	[1]
Legacy Loans And Leases [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	282,233	[2]	289,155	[2]
Legacy Loans And Leases [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	311,843	[3]	339,811	[3]
Legacy Loans And Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	4,112,780		3,659,499
Legacy Loans And Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	26,926	[4]	34,810	[4]
Purchased Loans And Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	2,276,005		614,634
Purchased Loans And Leases [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	1,584,409		245,524
Purchased Loans And Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	691,597		369,110
Purchased Loans And Leases [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	1,221,661	[1]	127,195	[1]
Purchased Loans And Leases [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	133,154	[2]	54,834	[2]
Purchased Loans And Leases [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	229,594	[3]	63,495	[3]
Purchased Loans And Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	679,633		368,205
Purchased Loans And Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	11,964	[4]	905	[4]
Commercial [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	2,168,708		1,871,027
Commercial [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	2,037,125	[1]	1,754,383	[1]
Commercial [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	67,490	[2]	56,066	[2]
Commercial [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	64,093	[3]	60,578	[3]
Commercial [Member] | Legacy Loans And Leases [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	1,993,709		1,867,041
Commercial [Member] | Legacy Loans And Leases [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	1,886,558	[1]	1,752,161	[1]
Commercial [Member] | Legacy Loans And Leases [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	61,405	[2]	54,902	[2]
Commercial [Member] | Legacy Loans And Leases [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	45,746	[3]	59,978	[3]
Commercial [Member] | Purchased Loans And Leases [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	174,999		3,986
Commercial [Member] | Purchased Loans And Leases [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	150,567	[1]	2,222	[1]
Commercial [Member] | Purchased Loans And Leases [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	6,085	[2]	1,164	[2]
Commercial [Member] | Purchased Loans And Leases [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	18,347	[3]	600	[3]
Real Estate - Construction [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	812,987	[5]	753,543	[5]
Real Estate - Construction [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	593,473	[1],[5]	561,536	[1],[5]
Real Estate - Construction [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	95,872	[2],[5]	97,252	[2],[5]
Real Estate - Construction [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	123,642	[3],[5]	94,755	[3],[5]
Real Estate - Construction [Member] | Legacy Loans And Leases [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	585,404	[5]	673,938	[5]
Real Estate - Construction [Member] | Legacy Loans And Leases [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	471,757	[1],[5]	552,897	[1],[5]
Real Estate - Construction [Member] | Legacy Loans And Leases [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	53,735	[2],[5]	60,945	[2],[5]
Real Estate - Construction [Member] | Legacy Loans And Leases [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	59,912	[3],[5]	60,096	[3],[5]
Real Estate - Construction [Member] | Purchased Loans And Leases [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	227,583	[5]	79,605	[5]
Real Estate - Construction [Member] | Purchased Loans And Leases [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	121,716	[1],[5]	8,639	[1],[5]
Real Estate - Construction [Member] | Purchased Loans And Leases [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	42,137	[2],[5]	36,307	[2],[5]
Real Estate - Construction [Member] | Purchased Loans And Leases [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	63,730	[3],[5]	34,659	[3],[5]
Real Estate - Secured - Commercial [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	4,862,609	[6]	3,759,941	[6]
Real Estate - Secured - Commercial [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	4,256,882	[1],[6]	3,321,297	[1],[6]
Real Estate - Secured - Commercial [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	252,025	[2],[6]	190,671	[2],[6]
Real Estate - Secured - Commercial [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	353,702	[3],[6]	247,973	[3],[6]
Real Estate - Secured - Commercial [Member] | Legacy Loans And Leases [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	3,680,782	[6]	3,598,008	[6]
Real Estate - Secured - Commercial [Member] | Legacy Loans And Leases [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	3,307,504	[1],[6]	3,204,963	[1],[6]
Real Estate - Secured - Commercial [Member] | Legacy Loans And Leases [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	167,093	[2],[6]	173,308	[2],[6]
Real Estate - Secured - Commercial [Member] | Legacy Loans And Leases [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	206,185	[3],[6]	219,737	[3],[6]
Real Estate - Secured - Commercial [Member] | Purchased Loans And Leases [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	1,181,827	[6]	161,933	[6]
Real Estate - Secured - Commercial [Member] | Purchased Loans And Leases [Member] | Pass [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	949,378	[1],[6]	116,334	[1],[6]
Real Estate - Secured - Commercial [Member] | Purchased Loans And Leases [Member] | Special Mention [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	84,932	[2],[6]	17,363	[2],[6]
Real Estate - Secured - Commercial [Member] | Purchased Loans And Leases [Member] | Substandard [Member] | Commercial Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	147,517	[3],[6]	28,236	[3],[6]
Real Estate - Secured - Residential [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	3,223,897		2,665,187
Real Estate - Secured - Residential [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	3,187,772		2,632,475
Real Estate - Secured - Residential [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	36,125	[4]	32,712	[4]
Real Estate - Secured - Residential [Member] | Legacy Loans And Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	2,544,856		2,296,360
Real Estate - Secured - Residential [Member] | Legacy Loans And Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	2,520,680		2,264,551
Real Estate - Secured - Residential [Member] | Legacy Loans And Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	24,176	[4]	31,809	[4]
Real Estate - Secured - Residential [Member] | Purchased Loans And Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	679,041		368,826
Real Estate - Secured - Residential [Member] | Purchased Loans And Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	667,092		367,923
Real Estate - Secured - Residential [Member] | Purchased Loans And Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	11,949	[4]	903	[4]
Consumer [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	829,760		722,329
Consumer [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	828,834		720,720
Consumer [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	926	[4]	1,609	[4]
Consumer [Member] | Legacy Loans And Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	817,204		722,045
Consumer [Member] | Legacy Loans And Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	816,293		720,438
Consumer [Member] | Legacy Loans And Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	911	[4]	1,607	[4]
Consumer [Member] | Purchased Loans And Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	12,556		284
Consumer [Member] | Purchased Loans And Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	12,541		282
Consumer [Member] | Purchased Loans And Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	15	[4]	2	[4]
Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	777,646		675,904
Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	775,807		674,510
Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	1,839	[4]	1,394	[4]
Leases [Member] | Legacy Loans And Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	777,646		675,904
Leases [Member] | Legacy Loans And Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	775,807		674,510
Leases [Member] | Legacy Loans And Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	1,839	[4]	1,394	[4]
Leases [Member] | Purchased Loans And Leases [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	0		0
Leases [Member] | Purchased Loans And Leases [Member] | Performing Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	0		0
Leases [Member] | Purchased Loans And Leases [Member] | Nonperforming Financing Receivable [Member] | Other Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Exposure	$ 0	[4]	$ 0	[4]

[1] Includes loans identified as having acceptable risk, which are loans for which the possibility of loss is considered unlikely.

[2] Includes loans considered potentially weak; however, no loss of principal or interest is anticipated.

[3] Includes loans that are inadequately protected by the current net-worth and paying capacity of the borrower or by the collateral pledged, if any. Loss of principal or interest is considered reasonably possible or likely.

[4] Includes loans that are on non-accrual status or past due ninety days or more.

[5] Includes only construction loans granted to commercial customers. Construction loans for individuals are included in Real Estate - Secured - Residential below.

[6] Includes loans obtained for commercial purposes that are also secured by residential real estate.