Loans and Leases (Impaired Loans) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012
Financing Receivable Impaired [Line Items]
Loans written down to fair value of collateral	$ 26,401		$ 28,658
Total impaired loans without a related reserve	196,753		201,186
Direct charge-offs	29,245		31,482
Subsequently Impaired Loans	5,650		6,625
Purchased Impaired Loans	156,525		162,251
Impaired Loans Without A Related Reserve [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	225,998		232,668
Recorded Investment in Impaired Loans	196,753	[1]	201,186	[2]
Related Charge-offs	29,245		31,482
Average Recorded Investment in Impaired Loans	204,562	[3]	202,781	[3]
Interest Income Recognized	2,996		3,243
Impaired Loans Without A Related Reserve [Member] | Originated Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	73,947		76,120
Recorded Investment in Impaired Loans	45,878		45,560
Related Charge-offs	28,069		30,560
Average Recorded Investment in Impaired Loans	55,862	[3]	49,975	[3]
Interest Income Recognized	794		764
Impaired Loans Without A Related Reserve [Member] | Purchased Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	152,051		156,548
Recorded Investment in Impaired Loans	150,875		155,626
Related Charge-offs	1,176		922
Average Recorded Investment in Impaired Loans	148,700	[3]	152,806	[3]
Interest Income Recognized	2,202		2,479
Impaired Loans Without A Related Reserve [Member] | Commercial, Financial, And Agricultural [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	25,675		23,959
Recorded Investment in Impaired Loans	23,787		23,877
Related Charge-offs	1,888		82
Average Recorded Investment in Impaired Loans	28,801	[3]	24,603	[3]
Interest Income Recognized	493		233
Impaired Loans Without A Related Reserve [Member] | Real Estate - Construction [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	24,486		48,394
Recorded Investment in Impaired Loans	17,715		32,717
Related Charge-offs	6,771		15,677
Average Recorded Investment in Impaired Loans	17,086	[3]	34,223	[3]
Interest Income Recognized	131		882
Impaired Loans Without A Related Reserve [Member] | Real Estate Secured - Residential [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	39,089		26,298
Recorded Investment in Impaired Loans	37,725		25,261
Related Charge-offs	1,364		1,037
Average Recorded Investment in Impaired Loans	38,306	[3]	25,417	[3]
Interest Income Recognized	500		398
Impaired Loans Without A Related Reserve [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	136,638		133,903
Recorded Investment in Impaired Loans	117,416		119,217
Related Charge-offs	19,222		14,686
Average Recorded Investment in Impaired Loans	120,261	[3]	118,424	[3]
Interest Income Recognized	1,869		1,727
Impaired Loans Without A Related Reserve [Member] | Consumer [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	110		114
Recorded Investment in Impaired Loans	110		114
Related Charge-offs	0		0
Average Recorded Investment in Impaired Loans	108	[3]	114	[3]
Interest Income Recognized	3		3
Impaired Loans With A Related Reserve [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	106,927		99,096
Recorded Investment in Impaired Loans	81,353		81,467
Related Charge-offs	25,574		17,629
Related Allowance	11,910		15,736
Average Recorded Investment in Impaired Loans	77,750	[3]	83,437	[3]
Interest Income Recognized	647		1,103
Impaired Loans With A Related Reserve [Member] | Originated Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	101,223		92,471
Recorded Investment in Impaired Loans	75,703		74,842
Related Charge-offs	25,520		17,629
Related Allowance	10,557		14,649
Average Recorded Investment in Impaired Loans	71,875	[3]	76,823	[3]
Interest Income Recognized	584		1,033
Impaired Loans With A Related Reserve [Member] | Purchased Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	5,704		6,625
Recorded Investment in Impaired Loans	5,650		6,625
Related Charge-offs	54		0
Related Allowance	1,353		1,087
Average Recorded Investment in Impaired Loans	5,875	[3]	6,614	[3]
Interest Income Recognized	63		70
Impaired Loans With A Related Reserve [Member] | Commercial, Financial, And Agricultural [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	10,315		4,240
Recorded Investment in Impaired Loans	10,187		4,184
Related Charge-offs	128		56
Related Allowance	3,429		3,267
Average Recorded Investment in Impaired Loans	4,480	[3]	4,278	[3]
Interest Income Recognized	36		47
Impaired Loans With A Related Reserve [Member] | Real Estate - Construction [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	25,194		12,894
Recorded Investment in Impaired Loans	10,675		5,577
Related Charge-offs	14,519		7,317
Related Allowance	732		952
Average Recorded Investment in Impaired Loans	12,762	[3]	5,883	[3]
Interest Income Recognized	4		237
Impaired Loans With A Related Reserve [Member] | Real Estate Secured - Residential [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	30,255		32,640
Recorded Investment in Impaired Loans	29,679		32,375
Related Charge-offs	576		265
Related Allowance	3,689		6,633
Average Recorded Investment in Impaired Loans	29,785	[3]	32,498	[3]
Interest Income Recognized	369		333
Impaired Loans With A Related Reserve [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	41,163		49,322
Recorded Investment in Impaired Loans	30,812		39,331
Related Charge-offs	10,351		9,991
Related Allowance	4,060		4,884
Average Recorded Investment in Impaired Loans	30,723	[3]	40,778	[3]
Interest Income Recognized	238		486
Impaired Loans With A Related Reserve [Member] | Consumer [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	0		0
Recorded Investment in Impaired Loans	0		0
Related Charge-offs	0		0
Related Allowance	0		0
Average Recorded Investment in Impaired Loans	0	[3]	0	[3]
Interest Income Recognized	0		0
Impaired Loans [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	332,925		331,764
Recorded Investment in Impaired Loans	278,106		282,653
Related Charge-offs	54,819		49,111
Related Allowance	11,910		15,736
Average Recorded Investment in Impaired Loans	282,312	[3]	286,218	[3]
Interest Income Recognized	3,643		4,346
Impaired Loans [Member] | Originated Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	175,170		168,591
Recorded Investment in Impaired Loans	121,581		120,402
Related Charge-offs	53,589		48,189
Related Allowance	10,557		14,649
Average Recorded Investment in Impaired Loans	127,737	[3]	126,798	[3]
Interest Income Recognized	1,378		1,797
Impaired Loans [Member] | Purchased Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	157,755	[4]	163,173	[5]
Recorded Investment in Impaired Loans	156,525	[4]	162,251	[5]
Related Charge-offs	1,230	[4]	922	[5]
Related Allowance	1,353	[4]	1,087	[5]
Average Recorded Investment in Impaired Loans	154,575	[3],[4]	159,420	[3],[5]
Interest Income Recognized	2,265	[4]	2,549	[5]
Impaired Loans [Member] | Commercial, Financial, And Agricultural [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	35,990		28,199
Recorded Investment in Impaired Loans	33,974		28,061
Related Charge-offs	2,016		138
Related Allowance	3,429		3,267
Average Recorded Investment in Impaired Loans	33,281	[3]	28,881	[3]
Interest Income Recognized	529		280
Impaired Loans [Member] | Real Estate - Construction [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	49,680		61,288
Recorded Investment in Impaired Loans	28,390		38,294
Related Charge-offs	21,290		22,994
Related Allowance	732		952
Average Recorded Investment in Impaired Loans	29,848	[3]	40,106	[3]
Interest Income Recognized	135		1,119
Impaired Loans [Member] | Real Estate Secured - Residential [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	69,344		58,938
Recorded Investment in Impaired Loans	67,404		57,636
Related Charge-offs	1,940		1,302
Related Allowance	3,689		6,633
Average Recorded Investment in Impaired Loans	68,091	[3]	57,915	[3]
Interest Income Recognized	869		731
Impaired Loans [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	177,801		183,225
Recorded Investment in Impaired Loans	148,228		158,548
Related Charge-offs	29,573		24,677
Related Allowance	4,060		4,884
Average Recorded Investment in Impaired Loans	150,984	[3]	159,202	[3]
Interest Income Recognized	2,107		2,213
Impaired Loans [Member] | Consumer [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	110		114
Recorded Investment in Impaired Loans	110		114
Related Charge-offs	0		0
Related Allowance	0		0
Average Recorded Investment in Impaired Loans	108	[3]	114	[3]
Interest Income Recognized	$ 3		$ 3

[1] $26,401 of the $196,753 total impaired loans without a related reserve represents loans that had been written down to the fair value of the underlying collateral through direct charge-offs of $29,245.

[2] $28,658 of the $201,186 total impaired loans without a related reserve represents loans that had been written down to the fair value of the underlying collateral through direct charge-offs of $31,482.

[3] Average recorded investment in impaired loans is calculated on a quarterly basis using daily balances.

[4] $5,650 of the $156,525 purchased impaired loans were subsequently impaired after being acquired.

[5] $6,625 of the $162,251 purchased impaired loans were subsequently impaired after being acquired.