Allowance For Loan & Lease Losses (Allowance For Credit Losses And Recorded Investment In Financing Receivables) (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	$ 154,150,000	$ 176,377,000	$ 157,608,000	$ 184,020,000
Charge-Offs	(15,942,000)	(17,438,000)	(29,342,000)	(41,531,000)
Recoveries	4,511,000	7,655,000	8,453,000	12,105,000
Transfer For Loans Designated As Held For Sale	(1,236,000)		(1,236,000)
Provision	3,000,000	12,000,000	9,000,000	24,000,000
Allowance For Credit Losses, Ending Balance	144,483,000	178,594,000	144,483,000	178,594,000
Individually evaluated for impairment	12,957,000	13,081,000	12,957,000	13,081,000
Collectively evaluated for impairment	131,526,000	165,513,000	131,526,000	165,513,000
Financing Receivables, Ending Balance	13,667,153,000	13,157,762,000	13,667,153,000	13,157,762,000
Financing receivables, Individually evaluated for impairment, Ending Balance	205,072,000	259,514,000	205,072,000	259,514,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	13,462,081,000	12,898,248,000	13,462,081,000	12,898,248,000
Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	11,556,000	13,081,000	11,556,000	13,081,000
Collectively evaluated for impairment	131,526,000	156,180,000	131,526,000	156,180,000
Financing receivables, Individually evaluated for impairment, Ending Balance	92,075,000	118,028,000	92,075,000	118,028,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	12,067,199,000	11,182,793,000	12,067,199,000	11,182,793,000
Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	1,401,000	0	1,401,000	0
Collectively evaluated for impairment	0	9,333,000	0	9,333,000
Financing receivables, Individually evaluated for impairment, Ending Balance	112,997,000	141,486,000	112,997,000	141,486,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	1,394,882,000	1,715,455,000	1,394,882,000	1,715,455,000
Commercial, Financial, And Agricultural [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	48,016,000	30,462,000	40,590,000	30,207,000
Charge-Offs	(9,094,000)	(10,829,000)	(13,608,000)	(20,866,000)
Recoveries	1,820,000	2,040,000	3,152,000	4,036,000
Transfer For Loans Designated As Held For Sale	0		0
Provision	659,000	8,564,000	11,267,000	16,860,000
Allowance For Credit Losses, Ending Balance	41,401,000	30,237,000	41,401,000	30,237,000
Individually evaluated for impairment	4,307,000	3,007,000	4,307,000	3,007,000
Collectively evaluated for impairment	37,094,000	27,230,000	37,094,000	27,230,000
Financing Receivables, Ending Balance	2,422,931,000	2,289,159,000	2,422,931,000	2,289,159,000
Financing receivables, Individually evaluated for impairment, Ending Balance	26,229,000	24,804,000	26,229,000	24,804,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	2,396,702,000	2,264,355,000	2,396,702,000	2,264,355,000
Commercial, Financial, And Agricultural [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	4,281,000	3,007,000	4,281,000	3,007,000
Collectively evaluated for impairment	37,094,000	27,104,000	37,094,000	27,104,000
Financing receivables, Individually evaluated for impairment, Ending Balance	16,378,000	10,905,000	16,378,000	10,905,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	2,262,865,000	2,142,345,000	2,262,865,000	2,142,345,000
Commercial, Financial, And Agricultural [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	26,000	0	26,000	0
Collectively evaluated for impairment	0	126,000	0	126,000
Financing receivables, Individually evaluated for impairment, Ending Balance	9,851,000	13,899,000	9,851,000	13,899,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	133,837,000	122,010,000	133,837,000	122,010,000
Real Estate - Construction [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	21,718,000	25,549,000	26,189,000	25,171,000
Charge-Offs	(339,000)	(1,170,000)	(630,000)	(5,933,000)
Recoveries	796,000	1,725,000	1,178,000	2,187,000
Transfer For Loans Designated As Held For Sale	0		0
Provision	(3,995,000)	(2,536,000)	(8,557,000)	2,143,000
Allowance For Credit Losses, Ending Balance	18,180,000	23,568,000	18,180,000	23,568,000
Individually evaluated for impairment	704,000	1,145,000	704,000	1,145,000
Collectively evaluated for impairment	17,476,000	22,423,000	17,476,000	22,423,000
Financing Receivables, Ending Balance	748,181,000	769,722,000	748,181,000	769,722,000
Financing receivables, Individually evaluated for impairment, Ending Balance	13,778,000	24,303,000	13,778,000	24,303,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	734,403,000	745,419,000	734,403,000	745,419,000
Real Estate - Construction [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	704,000	1,145,000	704,000	1,145,000
Collectively evaluated for impairment	17,476,000	22,013,000	17,476,000	22,013,000
Financing receivables, Individually evaluated for impairment, Ending Balance	3,283,000	10,948,000	3,283,000	10,948,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	686,743,000	649,535,000	686,743,000	649,535,000
Real Estate - Construction [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	0	410,000	0	410,000
Financing receivables, Individually evaluated for impairment, Ending Balance	10,495,000	13,355,000	10,495,000	13,355,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	47,660,000	95,884,000	47,660,000	95,884,000
Real Estate Secured - Residential [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	22,078,000	36,542,000	24,076,000	41,276,000
Charge-Offs	(3,290,000)	(2,607,000)	(7,120,000)	(5,620,000)
Recoveries	837,000	601,000	1,871,000	1,252,000
Transfer For Loans Designated As Held For Sale	0		0
Provision	1,751,000	3,180,000	2,549,000	808,000
Allowance For Credit Losses, Ending Balance	21,376,000	37,716,000	21,376,000	37,716,000
Individually evaluated for impairment	2,634,000	3,629,000	2,634,000	3,629,000
Collectively evaluated for impairment	18,742,000	34,087,000	18,742,000	34,087,000
Financing Receivables, Ending Balance	4,178,842,000	4,098,938,000	4,178,842,000	4,098,938,000
Financing receivables, Individually evaluated for impairment, Ending Balance	44,632,000	70,939,000	44,632,000	70,939,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	4,134,210,000	4,027,999,000	4,134,210,000	4,027,999,000
Real Estate Secured - Residential [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	2,181,000	3,629,000	2,181,000	3,629,000
Collectively evaluated for impairment	18,742,000	26,965,000	18,742,000	26,965,000
Financing receivables, Individually evaluated for impairment, Ending Balance	24,201,000	31,226,000	24,201,000	31,226,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	3,560,563,000	3,211,466,000	3,560,563,000	3,211,466,000
Real Estate Secured - Residential [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	453,000	0	453,000	0
Collectively evaluated for impairment	0	7,122,000	0	7,122,000
Financing receivables, Individually evaluated for impairment, Ending Balance	20,431,000	39,713,000	20,431,000	39,713,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	573,647,000	816,533,000	573,647,000	816,533,000
Real Estate Secured - Commercial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	44,486,000	66,977,000	48,261,000	70,053,000
Charge-Offs	(1,077,000)	(842,000)	(3,684,000)	(5,445,000)
Recoveries	347,000	2,083,000	820,000	2,805,000
Transfer For Loans Designated As Held For Sale	0		0
Provision	3,196,000	609,000	1,555,000	1,414,000
Allowance For Credit Losses, Ending Balance	46,952,000	68,827,000	46,952,000	68,827,000
Individually evaluated for impairment	5,198,000	5,155,000	5,198,000	5,155,000
Collectively evaluated for impairment	41,754,000	63,672,000	41,754,000	63,672,000
Financing Receivables, Ending Balance	4,053,990,000	4,029,454,000	4,053,990,000	4,029,454,000
Financing receivables, Individually evaluated for impairment, Ending Balance	119,384,000	138,017,000	119,384,000	138,017,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	3,934,606,000	3,891,437,000	3,934,606,000	3,891,437,000
Real Estate Secured - Commercial [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	4,276,000	5,155,000	4,276,000	5,155,000
Collectively evaluated for impairment	41,754,000	61,997,000	41,754,000	61,997,000
Financing receivables, Individually evaluated for impairment, Ending Balance	47,167,000	63,615,000	47,167,000	63,615,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	3,301,084,000	3,218,759,000	3,301,084,000	3,218,759,000
Real Estate Secured - Commercial [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	922,000	0	922,000	0
Collectively evaluated for impairment	0	1,675,000	0	1,675,000
Financing receivables, Individually evaluated for impairment, Ending Balance	72,217,000	74,402,000	72,217,000	74,402,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	633,522,000	672,678,000	633,522,000	672,678,000
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	2,097,000	2,997,000	2,266,000	3,722,000
Charge-Offs	(1,341,000)	(788,000)	(2,579,000)	(1,346,000)
Recoveries	328,000	239,000	711,000	561,000
Transfer For Loans Designated As Held For Sale	(1,236,000)		(1,236,000)
Provision	1,428,000	707,000	2,114,000	218,000
Allowance For Credit Losses, Ending Balance	1,276,000	3,155,000	1,276,000	3,155,000
Individually evaluated for impairment	114,000	145,000	114,000	145,000
Collectively evaluated for impairment	1,162,000	3,010,000	1,162,000	3,010,000
Financing Receivables, Ending Balance	962,618,000	908,328,000	962,618,000	908,328,000
Financing receivables, Individually evaluated for impairment, Ending Balance	1,049,000	1,451,000	1,049,000	1,451,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	961,569,000	906,877,000	961,569,000	906,877,000
Consumer [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	114,000	145,000	114,000	145,000
Collectively evaluated for impairment	1,162,000	3,010,000	1,162,000	3,010,000
Financing receivables, Individually evaluated for impairment, Ending Balance	1,046,000	1,334,000	1,046,000	1,334,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	955,353,000	898,527,000	955,353,000	898,527,000
Consumer [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	0	0	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	3,000	117,000	3,000	117,000
Financing receivables, Collectively evaluated for impairment, Ending Balance	6,216,000	8,350,000	6,216,000	8,350,000
Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	14,788,000	13,714,000	15,259,000	13,341,000
Charge-Offs	(801,000)	(1,202,000)	(1,721,000)	(2,321,000)
Recoveries	383,000	967,000	721,000	1,264,000
Transfer For Loans Designated As Held For Sale	0		0
Provision	(495,000)	1,271,000	(384,000)	2,466,000
Allowance For Credit Losses, Ending Balance	13,875,000	14,750,000	13,875,000	14,750,000
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	13,875,000	14,750,000	13,875,000	14,750,000
Financing Receivables, Ending Balance	1,300,591,000	1,062,161,000	1,300,591,000	1,062,161,000
Financing receivables, Individually evaluated for impairment, Ending Balance	0	0	0	0
Financing receivables, Collectively evaluated for impairment, Ending Balance	1,300,591,000	1,062,161,000	1,300,591,000	1,062,161,000
Leases [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	13,875,000	14,750,000	13,875,000	14,750,000
Financing receivables, Individually evaluated for impairment, Ending Balance	0	0	0	0
Financing receivables, Collectively evaluated for impairment, Ending Balance	1,300,591,000	1,062,161,000	1,300,591,000	1,062,161,000
Leases [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	0	0	0	0
Financing receivables, Individually evaluated for impairment, Ending Balance	0	0	0	0
Financing receivables, Collectively evaluated for impairment, Ending Balance	0	0	0	0
Unallocated [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance For Credit Losses, Beginning Balance	967,000	136,000	967,000	250,000
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Transfer For Loans Designated As Held For Sale	0		0
Provision	456,000	205,000	456,000	91,000
Allowance For Credit Losses, Ending Balance	1,423,000	341,000	1,423,000	341,000
Collectively evaluated for impairment	1,423,000	341,000	1,423,000	341,000
Unallocated [Member] | Originated Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collectively evaluated for impairment	1,423,000	341,000	1,423,000	341,000
Unallocated [Member] | Purchased Loans And Leases [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collectively evaluated for impairment	$ 0	$ 0	$ 0	$ 0