Fair Value of Financial Instruments - Carrying Values and Fair Values of Non-Current Financial Assets and Liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	$ 97	$ 125
Other noncurrent liabilities	(2,294)	(2,372)
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	97	125
Total noncurrent financial assets	97	125
Senior Notes	(6,795)	(5,928)
Commercial paper	(3,069)	(2,245)
Other long-term debt	(167)	(184)
Other noncurrent liabilities	(143)	(153)
Total noncurrent financial liabilities	(10,174)	(8,510)
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	94	116
Total noncurrent financial assets	94	116
Senior Notes	(6,994)	(5,794)
Commercial paper	(3,069)	(2,245)
Other long-term debt	(175)	(182)
Other noncurrent liabilities	(143)	(153)
Total noncurrent financial liabilities	$ (10,381)	$ (8,374)