Loans and Leases (Schedule of Modifications for Troubled Debt Restructurings) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012 Contract		Sep. 30, 2011 Contract		Sep. 30, 2012 Contract		Sep. 30, 2011 Contract
Financing Receivable, Modifications [Line Items]
Number of Loans	109				127
Pre-Modification Recorded Investment	$ 7,635				$ 12,958
Post-Modification Recorded Investment	7,635				12,958
Financial Effect of Modification on Recorded Investment	0	[1]			0	[1]
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans					127
Pre-Modification Recorded Investment					12,958
Post-Modification Recorded Investment					12,958
Financial Effect of Modification on Recorded Investment					0	[1]
Legacy Loans And Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	87				97
Pre-Modification Recorded Investment	5,370				8,255
Post-Modification Recorded Investment	5,370				8,255
Financial Effect of Modification on Recorded Investment	0	[1]			0	[1]
Purchased Loans And Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	22				30
Pre-Modification Recorded Investment	2,265				4,703
Post-Modification Recorded Investment	2,265				4,703
Financial Effect of Modification on Recorded Investment	0	[1]			0	[1]
Principal Deferral [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	0		0		0		1
Pre-Modification Recorded Investment	0		0		0		199
Post-Modification Recorded Investment	0		0		0		199
Financial Effect of Modification on Recorded Investment	0	[1]	0	[1]	0	[1]	0	[1]
Interest Rate Reduction [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	0		0		0		1
Pre-Modification Recorded Investment	0		0		0		336
Post-Modification Recorded Investment	0		0		0		336
Financial Effect of Modification on Recorded Investment	0	[1]	0	[1]	0	[1]	0	[1]
Interest Rate Reduction [Member] | Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	0		0		0		1
Pre-Modification Recorded Investment	0		0		0		88
Post-Modification Recorded Investment	0		0		0		88
Financial Effect of Modification on Recorded Investment	0	[1]	0	[1]	0	[1]	0	[1]
Other [Member] | Commercial, Financial, And Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	6	[2]	1	[2]	8	[2]	7	[3]
Pre-Modification Recorded Investment	457	[2]	331	[2]	787	[2]	2,165	[3]
Post-Modification Recorded Investment	457	[2]	331	[2]	787	[2]	2,165	[3]
Financial Effect of Modification on Recorded Investment	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[3]
Combination Of Concession Types [Member] | Real Estate Secured - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	3		2		17		23
Pre-Modification Recorded Investment	230		803		4,213		5,142
Post-Modification Recorded Investment	230		803		4,213		5,142
Financial Effect of Modification on Recorded Investment	0	[1]	0	[1]	0	[1]	0	[1]
Combination Of Concession Types [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	0		3		0		1
Pre-Modification Recorded Investment	0		5,220		0		1,877
Post-Modification Recorded Investment	0		5,220		0		1,877
Financial Effect of Modification on Recorded Investment	0	[1]	0	[1]	0	[1]	0	[1]
Combination Of Concession Types [Member] | Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	109		10				44
Pre-Modification Recorded Investment	7,635		6,639				11,143
Post-Modification Recorded Investment	7,635		6,639				11,143
Financial Effect of Modification on Recorded Investment	0	[1]	0	[1]			0	[1]
Other [Member] | Real Estate - Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	2	[2]	0	[2]	2	[2]	0	[3]
Pre-Modification Recorded Investment	343	[2]	0	[2]	343	[2]	0	[3]
Post-Modification Recorded Investment	343	[2]	0	[2]	343	[2]	0	[3]
Financial Effect of Modification on Recorded Investment	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[3]
Other [Member] | Real Estate Secured - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	57	[2]	4	[2]	59	[2]	9	[3]
Pre-Modification Recorded Investment	4,766	[2]	285	[2]	5,776	[2]	1,275	[3]
Post-Modification Recorded Investment	4,766	[2]	285	[2]	5,776	[2]	1,275	[3]
Financial Effect of Modification on Recorded Investment	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[3]
Other [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	6	[2]	0	[2]	6	[2]	0	[3]
Pre-Modification Recorded Investment	1,539	[2]	0	[2]	1,539	[2]	0	[3]
Post-Modification Recorded Investment	1,539	[2]	0	[2]	1,539	[2]	0	[3]
Financial Effect of Modification on Recorded Investment	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[3]
Other [Member] | Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	35	[2]	0	[2]	35	[2]	1	[3]
Pre-Modification Recorded Investment	300	[2]	0	[2]	300	[2]	61	[3]
Post-Modification Recorded Investment	300	[2]	0	[2]	300	[2]	61	[3]
Financial Effect of Modification on Recorded Investment	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[3]
Subsequently Defaulted [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	6		3		9		13
Financial Effect of Modification on Recorded Investment	1,191		3,681		2,531		20,550
Subsequently Defaulted [Member] | Commercial, Financial, And Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1		2		1		3
Financial Effect of Modification on Recorded Investment	351		2,081		351		2,543
Subsequently Defaulted [Member] | Real Estate - Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	0		0		0		2
Financial Effect of Modification on Recorded Investment	0		0		0		354
Subsequently Defaulted [Member] | Real Estate Secured - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	4		0		7		1
Financial Effect of Modification on Recorded Investment	641		0		1,981		118
Subsequently Defaulted [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1		1		1		6
Financial Effect of Modification on Recorded Investment	199		1,600		199		17,051
Subsequently Defaulted [Member] | Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	0		0		0		1
Financial Effect of Modification on Recorded Investment	0		0		0		484
Subsequently Defaulted [Member] | Legacy Loans And Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	5				8
Financial Effect of Modification on Recorded Investment	817				2,157
Subsequently Defaulted [Member] | Purchased Loans And Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1				1
Financial Effect of Modification on Recorded Investment	$ 374				$ 374

[1] Financial effects impacting the recorded investment include principal payments, advances, charge-offs, and capitalized past-due amounts.

[2] Bankruptcies and maturity date extensions.

[3] Maturity date extensions.