Merger Related Expenses (Detail) (Acquisition-related Costs, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	$ 2,500
Salaries and Employee Benefits
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	803
Outside Data Services
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	800
Professional fees (legal, consulting, etc.)
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	770
Miscellaneous Expenses
Business Acquisition, Contingent Consideration [Line Items]
Total merger expenses	$ 127