v2.4.0.6
Fair Value of Available for Sale Securities and Related Gains and Losses Recognized in Accumulated Other Comprehensive Income or Loss (Detail) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 294,962 $ 317,493
Gross Unrealized Gains 7,605 5,095
Gross Unrealized Losses (23) (76)
Fair Value 302,544 322,512
US Treasury and Government [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 112,473 168,104
Gross Unrealized Gains 1,313 1,368
Gross Unrealized Losses (23) (12)
Fair Value 113,763 169,460
Residential Mortgage Backed Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 181,429 148,329
Gross Unrealized Gains 6,292 3,727
Gross Unrealized Losses 0 (64)
Fair Value 187,721 151,992
Corporate Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 1,060 1,060
Gross Unrealized Gains 0 0
Gross Unrealized Losses 0 0
Fair Value $ 1,060 $ 1,060