Fair Value of Financial Instruments - Carrying Values and Fair Values of Non-Current Financial Assets and Liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	$ 275	$ 245
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	275	245
Total noncurrent financial assets	275	245
Senior Notes	(5,088)	(5,438)
Commercial paper	(2,431)	(2,311)
Other long-term debt	(224)	(280)
Total noncurrent financial liabilities	(7,743)	(8,029)
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	260	231
Total noncurrent financial assets	260	231
Senior Notes	(5,155)	(5,394)
Commercial paper	(2,431)	(2,311)
Other long-term debt	(227)	(284)
Total noncurrent financial liabilities	$ (7,813)	$ (7,989)