Debt - Narrative (Details) - USD ($)									12 Months Ended
	Dec. 17, 2018	May 15, 2018	Nov. 17, 2017	Nov. 02, 2017	Sep. 15, 2017	Jun. 29, 2017	Mar. 15, 2017	Oct. 14, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Payments on borrowings									$ 574,000,000	$ 1,554,000,000	$ 653,000,000
Short-term debt									$ 414,000,000	$ 6,000,000
Face amount					$ 1,000,000,000
Proceeds from debt					$ 993,000,000
Tranche One [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)					3.10%
Face amount					$ 700,000,000
Tranche Two [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)					3.90%
Face amount					$ 300,000,000
Notes [Member] | Notes due 2017 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)										5.30%
Payments on borrowings							$ 250,000,000
Notes [Member] | Senior notes due 2024 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)									0.75%	0.75%
Notes [Member] | Notes due 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)									5.60%	5.60%
Payments on borrowings		$ 450,000,000
Notes [Member] | Notes due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)									3.47%	3.47%
Notes [Member] | Notes due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)									3.68%	3.68%
Japanese Yen notes payable [Member] | Japanese Yen notes due 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)									4.215%	4.215%
Payments on borrowings	$ 88,000,000
Debenture [Member] | Debentures due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)									3.875%	3.875%
Debenture [Member] | Debenture due 2017 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)										6.10%
Payments on borrowings						$ 289,000,000
Senior Notes [Member] | Senior notes due 2017 [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate (in percentage)										1.50%
Payments on borrowings				$ 1,000,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity									$ 2,000,000,000
Revolving Credit Facility [Member] | Refinanced three-year revolving credit facility [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity			$ 500,000,000
Revolving credit facility, term (in years)			3 years
Revolving Credit Facility [Member] | Refinanced Five-Year Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity			$ 750,000,000
Revolving credit facility, term (in years)			5 years
Revolving Credit Facility [Member] | Five-Year Revolving Credit Facility, Expires October 14, 2021 [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity								$ 750,000,000
Revolving credit facility, term (in years)								5 years
Letter of Credit [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity									1,079,000,000
Letters of credit outstanding, amount									265,000,000
UNITED STATES | Commercial Paper [Member]
Debt Instrument [Line Items]
Short-term debt									$ 388,000,000
Weighted average interest rate									2.97%
Foreign [Member]
Debt Instrument [Line Items]
Short-term debt									$ 26,000,000