Business Combinations - Additional Information (Detail) (USD $)	9 Months Ended				3 Months Ended	9 Months Ended		1 Months Ended		1 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013 Core deposit intangible	Sep. 30, 2013 First Bank Of Delaware	Sep. 30, 2013 First Bank Of Delaware Core deposit intangible	Jun. 30, 2013 Davidson Trust Company	Sep. 30, 2013 Davidson Trust Company	Sep. 30, 2013 Davidson Trust Company Wealth Management	Nov. 14, 2012 Davidson Trust Company First Payment	Sep. 30, 2013 Davidson Trust Company First Payment	May 14, 2013 Davidson Trust Company Second Payment	Sep. 30, 2013 Davidson Trust Company Second Payment	Sep. 30, 2013 Davidson Trust Company Third Payment	Sep. 30, 2013 Davidson Trust Company Customer relationships	Sep. 30, 2013 Davidson Trust Company Non competition agreements
Business Acquisition [Line Items]
Business acquisition date			Nov. 17, 2012			May 15, 2012
Total capitalization of First Bank of Delaware			$ 250,000,000
Intangible assets, useful life, in years		10 years		10 years									10 years	5 years
Contingent payable amount									1,050,000		1,050,000	1,050,000
Contingent payments date									Nov. 14, 2012		May 14, 2013	Nov. 14, 2013
Payment of contingent consideration								1,050,000		1,050,000
Amount of future contingent payment												1,050,000
Corporation's wealth management divisions assets increased under management							1,000,000,000
Increase in Deferred tax asset					54,000
Decrease in goodwill	$ (54,000)					$ (54,000)