v2.4.0.6
Reconciliation of Assets Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs Level Three (Detail) (Corporate Securities, USD $)
In Thousands, unless otherwise specified
6 Months Ended12 Months Ended
Jun. 30, 2012
Dec. 31, 2011
Corporate Securities
  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]  
Balance of recurring Level 3 assets at January 1$ 1,060$ 1,060
Purchases00
Sales00
Issuances00
Settlements00
Transfers into Level 300
Transfers out of Level 300
Balance of recurring Level 3 assets at December 31$ 1,060$ 1,060