XML 24 R42.htm IDEA: XBRL DOCUMENT v2.4.0.6
Changes in Level 3 Financial Assets Measured at Fair Value on Recurring Basis (Detail) (Auction rate securities, USD $)
In Millions, unless otherwise specified
9 Months Ended 12 Months Ended
Sep. 30, 2012
Dec. 31, 2011
Auction rate securities
   
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Fair value at beginning of period $ 22 $ 22
Total losses included in earnings      
Unrealized (losses)      
Purchases      
Settlements      
Transfer from Level 3 to Level 2      
Fair value at period end $ 22 $ 22