Debt (First Lien Notes) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt		$ 10,901	$ 11,857
2022 First Lien Notes
Debt Instrument [Line Items]
Long-term debt	[1]	0
Early Repayment of Senior Debt	[1]	245
2024 First Lien Notes
Debt Instrument [Line Items]
Long-term debt	[2]	0
Early Repayment of Senior Debt	[2]	184
2026 First Lien Notes
Debt Instrument [Line Items]
Long-term debt		1,173	1,172
2028 First Lien Notes
Debt Instrument [Line Items]
Long-term debt		1,235	1,234
First Lien Notes
Debt Instrument [Line Items]
Long-term debt		$ 2,408	$ 2,835

[1] On January 21, 2020, we redeemed the outstanding $245 million in aggregate principal amount of our 2022 First Lien Notes, which was included in debt, current portion on our Consolidated Condensed Balance Sheet at December 31, 2019, with the proceeds from the 2028 First Lien Notes, which was included in cash and cash equivalents on our Consolidated Condensed Balance Sheet at

[2] (2)On January 21, 2020, we redeemed the outstanding $184 million in aggregate principal amount of our 2024 First Lien Notes, which was included in debt, current portion on our Consolidated Condensed Balance Sheet at December 31, 2019, with the proceeds from the 2028 First Lien Notes, which was included in cash and cash equivalents on our Consolidated Condensed Balance Sheet at December 31, 2019.