Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Jul. 02, 2012	Sep. 30, 2012 Series B Preferred Stock [Member]	Jun. 19, 2012 Series B Preferred Stock [Member]	Dec. 31, 2011 Series B Preferred Stock [Member]	Sep. 30, 2012 Series A Preferred Stock [Member]	Dec. 31, 2011 Series A Preferred Stock [Member]
Class of Stock [Line Items]
Nonaccrual status of loans	90 days
Amortization of intangible assets	10 years
Unrealized gain on available for sale securities	$ 4,168	$ 4,019
Minimum pension liability adjustment	1,818	1,818
Preferred stock, shares authorized	1,000,000			25,223		25,223	150,000	150,000
Preferred stock, par value	$ 0
Preferred stock, shares issued				25,223		25,223
Preferred stock, outstanding				25,223		25,223
Sale of shares				25,223		25,223
Purchase the Series B preferred stock from Treasury				$ 856.1325
Fixed Rate Cumulative Perpetual Preferred Stock offering price					869.17
Warrant to purchase share	561,343
Warrant repurchased mutually agreed price			$ 860