v2.4.0.6
Amortized Cost Unrecognized Gains and Losses and Fair Value of Securities Held to Maturity (Detail) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost $ 58,314 $ 48,975
US States and Political Subdivisions Debt Securities [Member]
   
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost 58,314 48,975
Gross Unrecognized Gains 2,169 1,693
Gross Unrecognized Losses (108) (25)
Fair Value $ 60,375 $ 50,643