Quarterly report pursuant to Section 13 or 15(d)

Long-term Debt - Summary of Components of Convertible Notes (Detail)

v3.8.0.1
Long-term Debt - Summary of Components of Convertible Notes (Detail) - 4.125% Convertible Senior Notes Due September 1, 2022 [Member] - USD ($)
$ in Millions
Sep. 30, 2017
Aug. 31, 2017
Debt Instrument [Line Items]    
Principal $ 150 $ 150
Accrued interest 1  
Unamortized financing costs (5)  
Carrying value of Convertible Notes $ 146 $ 145