Loans and Leases (Impaired Loans) (Detail) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2013		Dec. 31, 2012
Financing Receivable Impaired [Line Items]
Loans written down to fair value of collateral	$ 28,703,000		$ 28,658,000
Total impaired loans without a related reserve	175,474,000		201,186,000
Direct charge-offs	29,439,000		31,482,000
Subsequently Impaired Loans	13,302,000		6,625,000
Purchased Impaired Loans	138,503,000		162,251,000
Impaired Loans Without A Related Reserve [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	204,913,000		232,668,000
Recorded Investment in Impaired Loans	175,474,000	[1]	201,186,000	[2]
Related Charge-offs	29,439,000		31,482,000
Average Recorded Investment in Impaired Loans	175,115,000	[3]	202,781,000	[3]
Interest Income Recognized	2,235,000		3,243,000
Impaired Loans Without A Related Reserve [Member] | Originated Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	78,752,000		76,120,000
Recorded Investment in Impaired Loans	50,273,000		45,560,000
Related Charge-offs	28,479,000		30,560,000
Average Recorded Investment in Impaired Loans	48,835,000	[3]	49,975,000	[3]
Interest Income Recognized	494,000		764,000
Impaired Loans Without A Related Reserve [Member] | Purchased Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	126,161,000		156,548,000
Recorded Investment in Impaired Loans	125,201,000		155,626,000
Related Charge-offs	960,000		922,000
Average Recorded Investment in Impaired Loans	126,280,000	[3]	152,806,000	[3]
Interest Income Recognized	1,741,000		2,479,000
Impaired Loans Without A Related Reserve [Member] | Commercial, Financial, And Agricultural [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	21,189,000		23,959,000
Recorded Investment in Impaired Loans	21,034,000		23,877,000
Related Charge-offs	155,000		82,000
Average Recorded Investment in Impaired Loans	21,385,000	[3]	24,603,000	[3]
Interest Income Recognized	281,000		233,000
Impaired Loans Without A Related Reserve [Member] | Real Estate - Construction [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	36,542,000		48,394,000
Recorded Investment in Impaired Loans	20,800,000		32,717,000
Related Charge-offs	15,742,000		15,677,000
Average Recorded Investment in Impaired Loans	20,686,000	[3]	34,223,000	[3]
Interest Income Recognized	60,000		882,000
Impaired Loans Without A Related Reserve [Member] | Real Estate Secured - Residential [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	33,099,000		26,298,000
Recorded Investment in Impaired Loans	30,296,000		25,261,000
Related Charge-offs	2,803,000		1,037,000
Average Recorded Investment in Impaired Loans	31,130,000	[3]	25,417,000	[3]
Interest Income Recognized	425,000		398,000
Impaired Loans Without A Related Reserve [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	113,829,000		133,903,000
Recorded Investment in Impaired Loans	103,090,000		119,217,000
Related Charge-offs	10,739,000		14,686,000
Average Recorded Investment in Impaired Loans	101,660,000	[3]	118,424,000	[3]
Interest Income Recognized	1,466,000		1,727,000
Impaired Loans Without A Related Reserve [Member] | Consumer [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	254,000		114,000
Recorded Investment in Impaired Loans	254,000		114,000
Related Charge-offs	0		0
Average Recorded Investment in Impaired Loans	254,000	[3]	114,000	[3]
Interest Income Recognized	3,000		3,000
Impaired Loans With A Related Reserve [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	107,548,000		99,096,000
Recorded Investment in Impaired Loans	88,954,000		81,467,000
Related Charge-offs	18,594,000		17,629,000
Related Allowance	15,305,000		15,736,000
Average Recorded Investment in Impaired Loans	88,721,000	[3]	83,437,000	[3]
Interest Income Recognized	1,433,000		1,103,000
Impaired Loans With A Related Reserve [Member] | Originated Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	94,063,000		92,471,000
Recorded Investment in Impaired Loans	75,652,000		74,842,000
Related Charge-offs	18,411,000		17,629,000
Related Allowance	11,718,000		14,649,000
Average Recorded Investment in Impaired Loans	74,879,000	[3]	76,823,000	[3]
Interest Income Recognized	1,167,000		1,033,000
Impaired Loans With A Related Reserve [Member] | Purchased Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	13,485,000		6,625,000
Recorded Investment in Impaired Loans	13,302,000		6,625,000
Related Charge-offs	183,000		0
Related Allowance	3,587,000		1,087,000
Average Recorded Investment in Impaired Loans	13,842,000	[3]	6,614,000	[3]
Interest Income Recognized	266,000		70,000
Impaired Loans With A Related Reserve [Member] | Commercial, Financial, And Agricultural [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	7,724,000		4,240,000
Recorded Investment in Impaired Loans	7,402,000		4,184,000
Related Charge-offs	322,000		56,000
Related Allowance	3,129,000		3,267,000
Average Recorded Investment in Impaired Loans	7,580,000	[3]	4,278,000	[3]
Interest Income Recognized	152,000		47,000
Impaired Loans With A Related Reserve [Member] | Real Estate - Construction [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	11,542,000		12,894,000
Recorded Investment in Impaired Loans	5,426,000		5,577,000
Related Charge-offs	6,116,000		7,317,000
Related Allowance	2,105,000		952,000
Average Recorded Investment in Impaired Loans	7,873,000	[3]	5,883,000	[3]
Interest Income Recognized	238,000		237,000
Impaired Loans With A Related Reserve [Member] | Real Estate Secured - Residential [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	33,988,000		32,640,000
Recorded Investment in Impaired Loans	32,887,000		32,375,000
Related Charge-offs	1,101,000		265,000
Related Allowance	2,614,000		6,633,000
Average Recorded Investment in Impaired Loans	32,878,000	[3]	32,498,000	[3]
Interest Income Recognized	491,000		333,000
Impaired Loans With A Related Reserve [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	52,554,000		49,322,000
Recorded Investment in Impaired Loans	41,499,000		39,331,000
Related Charge-offs	11,055,000		9,991,000
Related Allowance	7,406,000		4,884,000
Average Recorded Investment in Impaired Loans	38,611,000	[3]	40,778,000	[3]
Interest Income Recognized	514,000		486,000
Impaired Loans With A Related Reserve [Member] | Consumer [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	1,740,000		0
Recorded Investment in Impaired Loans	1,740,000		0
Related Charge-offs	0		0
Related Allowance	51,000		0
Average Recorded Investment in Impaired Loans	1,779,000	[3]	0	[3]
Interest Income Recognized	38,000		0
Impaired Loans [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	312,461,000		331,764,000
Recorded Investment in Impaired Loans	264,428,000		282,653,000
Related Charge-offs	48,033,000		49,111,000
Related Allowance	15,305,000		15,736,000
Average Recorded Investment in Impaired Loans	263,836,000	[3]	286,218,000	[3]
Interest Income Recognized	3,668,000		4,346,000
Impaired Loans [Member] | Originated Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	172,815,000		168,591,000
Recorded Investment in Impaired Loans	125,925,000		120,402,000
Related Charge-offs	46,890,000		48,189,000
Related Allowance	11,718,000		14,649,000
Average Recorded Investment in Impaired Loans	123,714,000	[3]	126,798,000	[3]
Interest Income Recognized	1,661,000		1,797,000
Impaired Loans [Member] | Purchased Loans And Leases [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	139,646,000	[4]	163,173,000	[5]
Recorded Investment in Impaired Loans	138,503,000	[4]	162,251,000	[5]
Related Charge-offs	1,143,000	[4]	922,000	[5]
Related Allowance	3,587,000	[4]	1,087,000	[5]
Average Recorded Investment in Impaired Loans	140,122,000	[3],[4]	159,420,000	[3],[5]
Interest Income Recognized	2,007,000	[4]	2,549,000	[5]
Impaired Loans [Member] | Commercial, Financial, And Agricultural [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	28,913,000		28,199,000
Recorded Investment in Impaired Loans	28,436,000		28,061,000
Related Charge-offs	477,000		138,000
Related Allowance	3,129,000		3,267,000
Average Recorded Investment in Impaired Loans	28,965,000	[3]	28,881,000	[3]
Interest Income Recognized	433,000		280,000
Impaired Loans [Member] | Real Estate - Construction [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	48,084,000		61,288,000
Recorded Investment in Impaired Loans	26,226,000		38,294,000
Related Charge-offs	21,858,000		22,994,000
Related Allowance	2,105,000		952,000
Average Recorded Investment in Impaired Loans	28,559,000	[3]	40,106,000	[3]
Interest Income Recognized	298,000		1,119,000
Impaired Loans [Member] | Real Estate Secured - Residential [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	67,087,000		58,938,000
Recorded Investment in Impaired Loans	63,183,000		57,636,000
Related Charge-offs	3,904,000		1,302,000
Related Allowance	2,614,000		6,633,000
Average Recorded Investment in Impaired Loans	64,008,000	[3]	57,915,000	[3]
Interest Income Recognized	916,000		731,000
Impaired Loans [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	166,383,000		183,225,000
Recorded Investment in Impaired Loans	144,589,000		158,548,000
Related Charge-offs	21,794,000		24,677,000
Related Allowance	7,406,000		4,884,000
Average Recorded Investment in Impaired Loans	140,271,000	[3]	159,202,000	[3]
Interest Income Recognized	1,980,000		2,213,000
Impaired Loans [Member] | Consumer [Member]
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	1,994,000		114,000
Recorded Investment in Impaired Loans	1,994,000		114,000
Related Charge-offs	0		0
Related Allowance	51,000		0
Average Recorded Investment in Impaired Loans	2,033,000	[3]	114,000	[3]
Interest Income Recognized	$ 41,000		$ 3,000

[1] $28,703 of the $175,474 total impaired loans without a related reserve represents loans that had been written down to the fair value of the underlying collateral adjusted for selling costs through direct charge-offs of $29,439.

[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 adjusted for selling costs through direct charge-offs of $31,482.

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

[4] $13,302 of the $138,503 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.