Long Term Debt - Consolidated Debt Obligations (Parenthetical) (Detail) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
OLLC $2.0 billion revolving credit facility [Member]    
Debt Obligations [Abstract]    
Senior Notes maturity date March 2018  
Revolving credit facility $ 2,000,000,000  
Senior Secured Notes [Member] | Notes Due 2021 [Member]    
Debt Obligations [Abstract]    
Senior Notes maturity date May 2021  
Estimated fair value of fixed rate debt 563,500,000 721,000,000
Senior Secured Notes [Member] | Notes Due 2022 [Member]    
Debt Obligations [Abstract]    
Senior Notes maturity date August 2022  
Estimated fair value of fixed rate debt $ 380,000,000