XML 39 R40.htm IDEA: XBRL DOCUMENT v2.4.0.6
Financial Instruments - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Dec. 31, 2012
Assets Sold under Agreements to Repurchase [Line Items]      
Fair value of long-term debt $ 774   $ 762
Carrying value of long-term debt 723   723
Accretion expense $ 0.7 $ 0.6  
6 3/4 % Senior Notes Due 2020
     
Assets Sold under Agreements to Repurchase [Line Items]      
Interest percentage 6.75%    
Debt maturity period 2020    
6.0% Senior Notes Due 2022
     
Assets Sold under Agreements to Repurchase [Line Items]      
Interest percentage 6.00%    
Debt maturity period 2022