Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Additional Information (Detail)

v2.4.0.6
Fair Value Measurements - Additional Information (Detail) (USD $)
Dec. 31, 2012
Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Carrying value of senior notes $ 900,000,000 $ 600,000,000
Fair Value, Inputs, Level 2
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Revolving bank credit facility $ 170,000,000 $ 117,000,000