Debt, Long-term debt (Details) € in Millions, $ in Millions	3 Months Ended
Mar. 31, 2020 EUR (€)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Long-term debt [Line Items]
Long-term debt		$ 12,162	$ 11,617
Current maturities of long-term debt		(3)	(3)
Long-term debt, non-current portion		12,159	11,614
Senior Notes due 2021, $1,000 million, 6.0% ($3 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2021
Face amount		$ 1,000
Stated interest rate (in hundredths)	6.00%	6.00%
Unamortized debt issuance cost		$ 3
Long-term debt		1,014	998
Senior Notes due 2024, $1,000 million, 5.75% ($5 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2024
Face amount		$ 1,000
Stated interest rate (in hundredths)	5.75%	5.75%
Unamortized debt issuance cost		$ 5
Long-term debt		995	995
Senior Notes due 2055, $1,000 million, 4.625% ($16 million of discount; $11 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2055
Face amount		$ 1,000
Stated interest rate (in hundredths)	4.625%	4.625%
Unamortized discount		$ 16
Unamortized debt issuance cost		11
Long-term debt		973	973
Term Loan due 2022, $4,000 million ($2 million of debt issuance costs)
Long-term debt [Line Items]
Maturity year	2022
Maximum borrowing capacity		4,000
Unamortized debt issuance cost		2
Long-term debt		1,948	1,950
Senior Revolving Credit Facility due 2022, $2,500 million [Member]
Long-term debt [Line Items]
Maturity year	2022
Maximum borrowing capacity		2,500
Long-term debt		$ 500	0
Guaranteed Notes due 2022, €750 million, 1.875% ($1 million of discount; $2 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2022
Face amount \| €	€ 750
Stated interest rate (in hundredths)	1.875%	1.875%
Unamortized discount		$ 1
Unamortized debt issuance cost		2
Long-term debt		819	841
Guaranteed Notes due 2023, $750 million, 4.0% ($4 million of discount; $2 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2023
Face amount		$ 750
Stated interest rate (in hundredths)	4.00%	4.00%
Unamortized discount		$ 4
Unamortized debt issuance cost		2
Long-term debt		$ 744	744
Guaranteed Notes due 2026, €500 million, 0.875% ($2 million of discount; $3 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2026
Face amount \| €	€ 500
Stated interest rate (in hundredths)	0.875%	0.875%
Unamortized discount		$ 2
Unamortized debt issuance cost		3
Long-term debt		542	555
Guaranteed Notes due 2027, $1,000 million, 3.5% ($8 million of discount; $6 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2027
Face amount		$ 1,000
Stated interest rate (in hundredths)	3.50%	3.50%
Unamortized discount		$ 8
Unamortized debt issuance cost		6
Long-term debt		1,103	1,023
Guaranteed Notes due 2027, $300 million, 8.1%
Long-term debt [Line Items]
Maturity year	2027
Face amount		$ 300
Stated interest rate (in hundredths)	8.10%	8.10%
Long-term debt		$ 300	300
Guaranteed Notes due 2031, €500 million, 1.625% ($6 million of discount; $3 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2031
Face amount \| €	€ 500
Stated interest rate (in hundredths)	1.625%	1.625%
Unamortized discount		$ 6
Unamortized debt issuance cost		3
Long-term debt		538	552
Guaranteed Notes due 2043, $750 million, 5.25% ($20 million of discount; $7 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2043
Face amount		$ 750
Stated interest rate (in hundredths)	5.25%	5.25%
Unamortized discount		$ 20
Unamortized debt issuance cost		7
Long-term debt		723	723
Guaranteed Notes due 2044, $1,000 million, 4.875% ($10 million of discount; $9 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2044
Face amount		$ 1,000
Stated interest rate (in hundredths)	4.875%	4.875%
Unamortized discount		$ 10
Unamortized debt issuance cost		9
Long-term debt		981	980
Guaranteed Notes due 2049, $1,000 million, 4.2% ($15 million of discount; $10 million of debt issuance cost)
Long-term debt [Line Items]
Maturity year	2049
Face amount		$ 1,000
Stated interest rate (in hundredths)	4.20%	4.20%
Unamortized discount		$ 15
Unamortized debt issuance cost		10
Long-term debt		975	975
Other long-term debt [Member]
Long-term debt [Line Items]
Long-term debt		$ 7	$ 8

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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