Long-Term Debt - Schedule of Maturities of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Long-term Debt, Fiscal Year Maturity
2018	$ 2,183
2019	1,359
2020	1,983
2021	345
2022	2,009
Thereafter	660
Total	8,539	$ 7,112
Amortization of Debt Discount and Debt Issuance Cost, net
2018	(42)
2019	(30)
2020	(8)
2021	(6)
2022	(7)
Thereafter	(6)
Total	(99)	(104)
Long-term debt	$ 8,440	$ 7,008