Fair Value of Financial Instruments - Carrying Values and Fair Values of Non-Current Financial Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	$ 154	$ 215
Other noncurrent liabilities	(901)	(891)
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	154	215
Marketable securities and other debt securities	46	44
Total noncurrent financial assets	200	259
Senior Notes	(2,273)	(2,272)
Commercial paper	(1,320)	(1,072)
Other long-term debt	(105)	(108)
Other noncurrent liabilities	(57)	(57)
Total noncurrent financial liabilities	(3,755)	(3,509)
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior, mezzanine, and other loans	151	214
Marketable securities and other debt securities	46	44
Total noncurrent financial assets	197	258
Senior Notes	(2,393)	(2,370)
Commercial paper	(1,320)	(1,072)
Other long-term debt	(119)	(122)
Other noncurrent liabilities	(57)	(57)
Total noncurrent financial liabilities	$ (3,889)	$ (3,621)