Debt - Summary of Long-term Debt (Details) $ in Millions	Jun. 30, 2020 USD ($)	Jun. 30, 2020 EUR (€)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 EUR (€)
Debt Instrument [Line Items]
Principal amount at par	$ 15,908		$ 14,873
Fair value	17,129		15,949
Senior Notes
Debt Instrument [Line Items]
Principal amount at par | €		€ 5,170,000,000
Senior Notes | 5.375% Senior Notes
Debt Instrument [Line Items]
Principal amount at par	500		500
Fair value	$ 512		$ 518
Interest rate	5.375%	5.375%	5.375%	5.375%
Senior Notes | 5.500% Senior Notes
Debt Instrument [Line Items]
Principal amount at par	$ 700		$ 700
Fair value	$ 733		$ 744
Interest rate	5.50%	5.50%	5.50%	5.50%
Senior Notes | 5.750% Senior Notes
Debt Instrument [Line Items]
Principal amount at par	$ 400		$ 400
Fair value	$ 437		$ 444
Interest rate	5.75%	5.75%	5.75%	5.75%
Senior Notes | 5.875% Senior Notes
Debt Instrument [Line Items]
Principal amount at par	$ 800		$ 800
Fair value	$ 892		$ 896
Interest rate	5.875%	5.875%	5.875%	5.875%
Senior Notes | 3.000% Senior Notes
Debt Instrument [Line Items]
Principal amount at par	$ 527	€ 470,000,000	$ 0	€ 470,000,000
Fair value	$ 545		$ 0
Interest rate	3.00%	3.00%	3.00%	3.00%
Senior Notes | 4.875% Senior Notes
Debt Instrument [Line Items]
Principal amount at par	$ 500		$ 0
Fair value	$ 504		$ 0
Interest rate	3.625%	3.625%	3.625%	3.625%
Senior Notes | Four Point Three Seven Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 1,000		$ 1,000
Fair value	$ 1,043		$ 1,026
Interest rate	4.375%	4.375%	4.375%	4.375%
Senior Notes | Three Point Six Two Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 1,461	€ 1,300,000,000	$ 1,459	€ 1,300,000,000
Fair value	$ 1,524		$ 1,565
Interest rate	3.625%	3.625%	3.625%	3.625%
Senior Notes | Four Point Eight Seven Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 1,600		$ 1,600
Fair value	$ 1,712		$ 1,670
Interest rate	4.875%	4.875%	4.875%	4.875%
Senior Notes | Five Point Eight Seven Five Percent Senior Notes 2018 [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 1,900		$ 1,900
Fair value	$ 2,164		$ 2,111
Interest rate	5.875%	5.875%	5.875%	5.875%
Senior Notes | Four Point Six Two Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 1,236	€ 1,100,000,000	$ 1,234	€ 1,100,000,000
Fair value	$ 1,375		$ 1,378
Interest rate	4.625%	4.625%	4.625%	4.625%
Senior Notes | Six Point Three Seven Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 800		$ 800
Fair value	$ 934		$ 916
Interest rate	6.375%	6.375%	6.375%	6.375%
Senior Notes | Three Point Eight Seven Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 1,348	€ 1,200,000,000	$ 1,346	€ 1,200,000,000
Fair value	$ 1,418		$ 1,429
Interest rate	3.875%	3.875%	3.875%	3.875%
Senior Notes | Five Point Three Seven Five Percent Senior Notes Issued April 2019 [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 900		$ 900
Fair value	$ 989		$ 960
Interest rate	5.375%	5.375%	5.375%	5.375%
Senior Notes | Three Point Six Two Five Percent Senior Notes Issued October 2019 [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 1,236	€ 1,100,000,000	$ 1,234	€ 1,100,000,000
Fair value	$ 1,274		$ 1,273
Interest rate	3.625%	3.625%	3.625%	3.625%
Senior Notes | Four Point Eight Seven Five Percent Senior Notes Issued October 2019 [Member]
Debt Instrument [Line Items]
Principal amount at par	$ 1,000		$ 1,000
Fair value	$ 1,073		$ 1,019
Interest rate	4.875%	4.875%	4.875%	4.875%