Long-Term Debt - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2014	Nov. 30, 2012
Debt Instrument [Line Items]
Credit Facility and Other Long Term Debt	$ 577,000,000	$ 588,000,000
Face amount outstanding	8,300,000,000
Unamortized discount	88,000,000	90,000,000
Total estimated fair value of notes	$ 8,700,000,000	$ 8,700,000,000
Other long-term debt, weighted average interest rate	2.90%	3.40%
May 2016 Revolving Credit Facility
Debt Instrument [Line Items]
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
Credit Agreement, borrowings outstanding	$ 0	$ 0
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%
October 2016 Revolving Credit Facility
Debt Instrument [Line Items]
Other long-term debt, weighted average interest rate	2.40%	2.30%
Debt Instrument, Collateral Amount	$ 588,000,000	$ 579,000,000
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%
Credit Agreement, borrowings outstanding	$ 500,000,000	$ 495,000,000
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