Allowance For Loan & Lease Losses (Allowance For Credit Losses And Recorded Investment In Financing Receivables) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	$ 157,608,000	$ 184,020,000
Charge-Offs	(13,400,000)	(24,093,000)
Recoveries	3,942,000	4,450,000
Provision	6,000,000	12,000,000
Allowance For Credit Losses, Ending Balance	154,150,000	176,377,000
Individually evaluated for impairment	16,155,000	11,910,000
Collectively evaluated for impairment	137,995,000	164,467,000
Financing Receivables, Ending Balance	13,575,295,000	12,999,703,000
Financing receivables, Individually evaluated for impairment, Ending Balance	212,580,000	278,106,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	13,362,715,000	12,721,597,000
Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	14,428,000	10,557,000
Collectively evaluated for impairment	137,995,000	164,467,000
Financing receivables, Individually evaluated for impairment, Ending Balance	95,509,000	121,581,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	11,898,509,000	10,876,717,000
Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	1,727,000	1,353,000
Collectively evaluated for impairment	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	117,071,000	156,525,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	1,464,206,000	1,844,880,000
Commercial, Financial, And Agricultural [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	40,590,000	30,207,000
Charge-Offs	(4,514,000)	(10,037,000)
Recoveries	1,332,000	1,996,000
Provision	10,608,000	8,296,000
Allowance For Credit Losses, Ending Balance	48,016,000	30,462,000
Individually evaluated for impairment	10,382,000	3,429,000
Collectively evaluated for impairment	37,634,000	27,033,000
Financing Receivables, Ending Balance	2,411,851,000	2,312,660,000
Financing receivables, Individually evaluated for impairment, Ending Balance	32,587,000	33,974,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	2,379,264,000	2,278,686,000
Commercial, Financial, And Agricultural [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	10,356,000	3,382,000
Collectively evaluated for impairment	37,634,000	27,033,000
Financing receivables, Individually evaluated for impairment, Ending Balance	22,192,000	18,015,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	2,244,677,000	2,113,397,000
Commercial, Financial, And Agricultural [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	26,000	47,000
Collectively evaluated for impairment	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	10,395,000	15,959,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	134,587,000	165,289,000
Real Estate - Construction [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	26,189,000	25,171,000
Charge-Offs	(291,000)	(4,763,000)
Recoveries	382,000	462,000
Provision	(4,562,000)	4,679,000
Allowance For Credit Losses, Ending Balance	21,718,000	25,549,000
Individually evaluated for impairment	875,000	732,000
Collectively evaluated for impairment	20,843,000	24,817,000
Financing Receivables, Ending Balance	714,291,000	779,344,000
Financing receivables, Individually evaluated for impairment, Ending Balance	17,122,000	28,391,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	697,169,000	750,953,000
Real Estate - Construction [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	875,000	719,000
Collectively evaluated for impairment	20,843,000	24,817,000
Financing receivables, Individually evaluated for impairment, Ending Balance	6,301,000	17,275,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	645,380,000	637,787,000
Real Estate - Construction [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	0	13,000
Collectively evaluated for impairment	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	10,821,000	11,116,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	51,789,000	113,166,000
Real Estate Secured - Residential [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	24,076,000	41,276,000
Charge-Offs	(3,830,000)	(3,013,000)
Recoveries	1,034,000	651,000
Provision	798,000	(2,372,000)
Allowance For Credit Losses, Ending Balance	22,078,000	36,542,000
Individually evaluated for impairment	2,679,000	3,689,000
Collectively evaluated for impairment	19,399,000	32,853,000
Financing Receivables, Ending Balance	4,178,505,000	4,077,810,000
Financing receivables, Individually evaluated for impairment, Ending Balance	44,455,000	54,397,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	4,134,050,000	4,023,413,000
Real Estate Secured - Residential [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	2,284,000	2,475,000
Collectively evaluated for impairment	19,399,000	32,853,000
Financing receivables, Individually evaluated for impairment, Ending Balance	23,669,000	29,108,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	3,535,917,000	3,150,965,000
Real Estate Secured - Residential [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	395,000	1,214,000
Collectively evaluated for impairment	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	20,786,000	25,289,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	598,133,000	872,448,000
Real Estate Secured - Commercial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	48,261,000	70,053,000
Charge-Offs	(2,607,000)	(4,603,000)
Recoveries	473,000	722,000
Provision	(1,641,000)	805,000
Allowance For Credit Losses, Ending Balance	44,486,000	66,977,000
Individually evaluated for impairment	2,098,000	4,060,000
Collectively evaluated for impairment	42,388,000	62,917,000
Financing Receivables, Ending Balance	4,041,989,000	3,971,438,000
Financing receivables, Individually evaluated for impairment, Ending Balance	117,294,000	161,234,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	3,924,695,000	3,810,204,000
Real Estate Secured - Commercial [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	793,000	3,981,000
Collectively evaluated for impairment	42,388,000	62,917,000
Financing receivables, Individually evaluated for impairment, Ending Balance	42,239,000	57,183,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	3,251,428,000	3,125,247,000
Real Estate Secured - Commercial [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	1,305,000	79,000
Collectively evaluated for impairment	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	75,055,000	104,051,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	673,267,000	684,957,000
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	2,266,000	3,722,000
Charge-Offs	(1,238,000)	(558,000)
Recoveries	383,000	322,000
Provision	686,000	(489,000)
Allowance For Credit Losses, Ending Balance	2,097,000	2,997,000
Individually evaluated for impairment	121,000	0
Collectively evaluated for impairment	1,976,000	2,997,000
Financing Receivables, Ending Balance	955,577,000	859,664,000
Financing receivables, Individually evaluated for impairment, Ending Balance	1,122,000	110,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	954,455,000	859,554,000
Consumer [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	120,000	0
Collectively evaluated for impairment	1,976,000	2,997,000
Financing receivables, Individually evaluated for impairment, Ending Balance	1,108,000	0
Financing receivables, Collectively evaluated for impairment, Ending Balance	948,025,000	850,534,000
Consumer [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	1,000	0
Collectively evaluated for impairment	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	14,000	110,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	6,430,000	9,020,000
Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	15,259,000	13,341,000
Charge-Offs	(920,000)	(1,119,000)
Recoveries	338,000	297,000
Provision	111,000	1,195,000
Allowance For Credit Losses, Ending Balance	14,788,000	13,714,000
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	14,788,000	13,714,000
Financing Receivables, Ending Balance	1,273,082,000	998,787,000
Financing receivables, Individually evaluated for impairment, Ending Balance	0	0
Financing receivables, Collectively evaluated for impairment, Ending Balance	1,273,082,000	998,787,000
Leases [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	14,788,000	13,714,000
Financing receivables, Individually evaluated for impairment, Ending Balance	0	0
Financing receivables, Collectively evaluated for impairment, Ending Balance	1,273,082,000	998,787,000
Leases [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	0	0
Financing receivables, Collectively evaluated for impairment, Ending Balance	0	0
Unallocated [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	967,000	250,000
Charge-Offs	0	0
Recoveries	0	0
Provision	0	(114,000)
Allowance For Credit Losses, Ending Balance	967,000	136,000
Collectively evaluated for impairment	967,000	136,000
Unallocated [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collectively evaluated for impairment	967,000	136,000
Unallocated [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collectively evaluated for impairment	$ 0	$ 0