Debt - Summary of Outstanding Debt (Details)	3 Months Ended
	Mar. 31, 2018 EUR (€)	Mar. 31, 2018 USD ($)	Jan. 31, 2018 EUR (€)	Jan. 31, 2018 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Short-term debt		$ 32,000,000				$ 62,000,000
Principal outstanding
Total long-term debt		7,911,000,000				5,328,000,000
Less: current maturities		(61,000,000)				(64,000,000)
Total long-term debt, less current maturities		7,850,000,000				5,264,000,000
Carrying amount
Total long-term debt		7,839,000,000				5,281,000,000
Less: current maturities		(61,000,000)				(64,000,000)
Total long-term debt, less current maturities		7,778,000,000				5,217,000,000
Capital lease obligations		29,000,000				29,000,000
Senior Secured Borrowings | U.S. dollar at LIBOR 1.50% due 2022
Principal outstanding
Total long-term debt		736,000,000				741,000,000
Carrying amount
Total long-term debt		730,000,000				735,000,000
Senior Secured Borrowings | Euro at EURIBOR 1.50% due 2022
Principal outstanding
Total long-term debt		330,000,000				324,000,000
Carrying amount
Total long-term debt		330,000,000				324,000,000
Debt, face amount	€ 268,000,000	924,000,000			€ 270,000,000
Senior Notes and Debentures | €650 at 4.0% due 2022
Principal outstanding
Total long-term debt		801,000,000				781,000,000
Carrying amount
Total long-term debt		$ 795,000,000				774,000,000
Debt instrument stated percentage	4.00%	4.00%
Debt, face amount | €	€ 650,000,000
Senior Notes and Debentures | U. S. dollar at 4.50% due 2023
Principal outstanding
Total long-term debt		$ 1,000,000,000				1,000,000,000
Carrying amount
Total long-term debt		$ 992,000,000				992,000,000
Debt instrument stated percentage	4.50%	4.50%
Senior Notes and Debentures | €335 at 2.250% due 2023
Principal outstanding
Total long-term debt		$ 413,000,000				0
Carrying amount
Total long-term debt		$ 407,000,000				0
Debt instrument stated percentage	2.25%	2.25%	2.25%	2.25%
Debt, face amount	€ 335,000,000	$ 413,000,000	€ 335,000,000
Senior Notes and Debentures | €600 at 2.625% due 2024
Principal outstanding
Total long-term debt		739,000,000				720,000,000
Carrying amount
Total long-term debt		$ 732,000,000				713,000,000
Debt instrument stated percentage	2.625%	2.625%
Debt, face amount | €	€ 600,000,000
Senior Notes and Debentures | €600 at 3.375% due 2025
Principal outstanding
Total long-term debt		$ 739,000,000				720,000,000
Carrying amount
Total long-term debt		$ 730,000,000				711,000,000
Debt instrument stated percentage	3.375%	3.375%
Debt, face amount | €	€ 600,000,000
Senior Notes and Debentures | U.S. dollar at 4.25% due 2026
Principal outstanding
Total long-term debt		$ 400,000,000				400,000,000
Carrying amount
Total long-term debt		$ 393,000,000				393,000,000
Debt instrument stated percentage	4.25%	4.25%
Senior Notes and Debentures | U.S. dollar at 4.75% due 2026
Principal outstanding
Total long-term debt		$ 875,000,000				0
Carrying amount
Total long-term debt		$ 863,000,000				0
Debt instrument stated percentage	4.75%	4.75%	4.75%	4.75%
Debt, face amount				$ 875,000,000
Senior Notes and Debentures | U.S. dollar at 7.375% due 2026
Principal outstanding
Total long-term debt		$ 350,000,000				350,000,000
Carrying amount
Total long-term debt		$ 347,000,000				347,000,000
Debt instrument stated percentage	7.375%	7.375%
Senior Notes and Debentures | €500 at 2.875% due 2026
Principal outstanding
Total long-term debt		$ 616,000,000				0
Carrying amount
Total long-term debt		$ 608,000,000				0
Debt instrument stated percentage	2.875%	2.875%	2.875%	2.875%
Debt, face amount	€ 500,000,000	$ 616,000,000	€ 500,000,000
Senior Notes and Debentures | U.S. dollar at 7.50% due 2096
Principal outstanding
Total long-term debt		40,000,000				40,000,000
Carrying amount
Total long-term debt		$ 40,000,000				40,000,000
Debt instrument stated percentage	7.50%	7.50%
Other Indebtedness, Fixed Rate
Principal outstanding
Total long-term debt		$ 94,000,000				101,000,000
Carrying amount
Total long-term debt		94,000,000				101,000,000
Revolving Credit Facility | Line of Credit
Principal outstanding
Total long-term debt		749,000,000				122,000,000
Carrying amount
Total long-term debt		$ 749,000,000				$ 122,000,000
London Interbank Offered Rate (LIBOR) | Senior Secured Borrowings | U.S. dollar at LIBOR 1.50% due 2022
Carrying amount
Basis spread on variable rate (as a percent)	1.50%
EURIBOR | Senior Secured Borrowings | Euro at EURIBOR 1.50% due 2022
Carrying amount
Basis spread on variable rate (as a percent)	1.50%