Earnings Per Share, Accumulated Other Comprehensive Loss, Dividend Restrictions and Other Regulatory Matters (Detail) - Schedule of components of accumulated other comprehensive loss (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Balance	$ (1,365)	$ (2,125)	$ (2,684)	$ (2,844)
Net change in other comprehensive loss	1,319	719
Unrealized (Loss) Gain On Securities Available For Sale [Member]
Balance	(390)	(1,170)	(1,709)	(1,889)
Net change in other comprehensive loss	1,319	719
Change In Pension Liability [Member]
Balance	(975)	(955)	(975)	(955)
Net change in other comprehensive loss	$ 0	$ 0