Credit Quality (Schedule of Troubled Debt Restructuring, Segregated by Class of Loans) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012 Contract	Jun. 30, 2012 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	2
Pre-Modification Outstanding Recorded Investment	$ 640	$ 1,371
Post-Modification Outstanding Recorded Investment	656	1,431
Owner-Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	1
Pre-Modification Outstanding Recorded Investment	0	731
Post-Modification Outstanding Recorded Investment	0	775
Nonowner-Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment	0	0
Other Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment	0	0
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	1
Pre-Modification Outstanding Recorded Investment	640	640
Post-Modification Outstanding Recorded Investment	656	656
Construction & Land Development [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment	0	0
Bankcard [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment	0	0
Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment	$ 0	$ 0