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
Sep. 30, 2012
Dec. 31, 2011
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months Fair Value $ 10,510 $ 58,666
Less than 12 Months Unrealized Loss (131) (100)
12 Months or More Fair Value 0 388
12 Months or More Unrealized Loss 0 (1)
Total Fair Value 10,510 59,054
Total Unrealized Loss (131) (101)
US Treasury and Government [Member]
   
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months Fair Value 4,992 18,734
Less than 12 Months Unrealized Loss (23) (12)
12 Months or More Fair Value 0 0
12 Months or More Unrealized Loss 0 0
Total Fair Value 4,992 18,734
Total Unrealized Loss (23) (12)
Residential Mortgage Backed Securities [Member]
   
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months Fair Value   36,707
Less than 12 Months Unrealized Loss   (64)
12 Months or More Fair Value   0
12 Months or More Unrealized Loss   0
Total Fair Value   36,707
Total Unrealized Loss   (64)
US States and Political Subdivisions Debt Securities [Member]
   
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months Fair Value   3,225
Less than 12 Months Unrealized Loss   (24)
12 Months or More Fair Value   388
12 Months or More Unrealized Loss   (1)
Total Fair Value   3,613
Total Unrealized Loss   (25)
Municipal and Other Obligations [Member]
   
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months Fair Value 5,518 3,225
Less than 12 Months Unrealized Loss (108) (24)
12 Months or More Fair Value 0 388
12 Months or More Unrealized Loss 0 (1)
Total Fair Value 5,518 3,613
Total Unrealized Loss $ (108) $ (25)