Long-Term Debt - Additional Information (Detail) - USD ($)	1 Months Ended		9 Months Ended	12 Months Ended
	Oct. 31, 2016	May 31, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 30, 2012
Debt Instrument [Line Items]
Face amount outstanding			$ 8,300,000,000
Unamortized discount			92,000,000		$ 97,000,000
Carrying amount of other long-term debt including current portion			95,000,000		312,000,000
Total estimated fair value of notes			$ 9,100,000,000		$ 8,500,000,000
Other long-term debt, weighted average interest rate			3.03%		3.74%
Credit Agreement, borrowings outstanding			$ 0		$ 0
May 2016 Revolving Credit Facility
Debt Instrument [Line Items]
Credit Agreement, initiation date		May 20, 2016
Credit Agreement, maximum borrowing capacity			$ 3,000,000,000
Credit Agreement, term			3 years
Credit Agreement, term additional information			may be extended for up to three additional one-year terms if approved by the lenders
Credit Agreement, variable rate basis			LIBOR
May 2016 Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Credit Agreement, basis spread on variable rate			0.60%
Credit Agreement, commitment fee			0.05%
May 2016 Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Credit Agreement, basis spread on variable rate			1.00%
Credit Agreement, commitment fee			0.09%
2014 Note
Debt Instrument [Line Items]
Face amount						$ 6,000,000,000
Interest payment frequency			semi-annually in arrears in June and December
2012 Note
Debt Instrument [Line Items]
Face amount							$ 3,000,000,000
Interest payment frequency			semi-annually in arrears in May and November
Oct16 Credit Facility | October 2016 Revolving Credit Facility
Debt Instrument [Line Items]
Credit Agreement, initiation date	Oct. 13, 2016
Credit Agreement, maximum borrowing capacity				$ 500,000,000
Credit Agreement, term				3 years
Credit Agreement, term additional information				secured by certain seller receivables
Credit Agreement, variable rate basis				LIBOR
Credit Agreement, basis spread on variable rate				1.65%
Credit Agreement, commitment fee				0.50%