Merger Related Expenses (Detail) (Acquisition-related Costs, USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	$ 2,708
Salaries And Employee Benefits
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	798
Outside Data Services
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	1,045
Professional Fees (legal, consulting, etc.)
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	732
Miscellaneous Expenses
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	$ 133