v2.4.0.6
Securities with Unrealized Losses Aggregated by Investment Category and Length of Time Individual Securities have been in Continuous Unrealized Loss Position (Detail) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Investments, Unrealized Loss Position [Line Items]  
Less than 12 Months Fair Value$ 41,284$ 58,666
Less than 12 Months Unrealized Loss(184)(100)
12 Months or More Fair Value0388
12 Months or More Unrealized Loss0(1)
Total Fair Value41,28459,054
Total Unrealized Loss(184)(101)
US Treasury and Government
  
Investments, Unrealized Loss Position [Line Items]  
Less than 12 Months Fair Value14,19318,734
Less than 12 Months Unrealized Loss(20)(12)
12 Months or More Fair Value00
12 Months or More Unrealized Loss00
Total Fair Value14,19318,734
Total Unrealized Loss(20)(12)
Residential Mortgage Backed Securities
  
Investments, Unrealized Loss Position [Line Items]  
Less than 12 Months Fair Value23,53236,707
Less than 12 Months Unrealized Loss(107)(64)
12 Months or More Fair Value00
12 Months or More Unrealized Loss00
Total Fair Value23,53236,707
Total Unrealized Loss(107)(64)
US States and Political Subdivisions Debt Securities
  
Investments, Unrealized Loss Position [Line Items]  
Less than 12 Months Fair Value3,5593,225
Less than 12 Months Unrealized Loss(57)(24)
12 Months or More Fair Value0388
12 Months or More Unrealized Loss0(1)
Total Fair Value3,5593,613
Total Unrealized Loss$ (57)$ (25)