Debt (Details)		3 Months Ended	9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 EUR (€)	May. 20, 2015 USD ($)	Feb. 02, 2015 USD ($)	Dec. 31, 2014 USD ($) credit_facility	Dec. 31, 2014 EUR (€) credit_facility
Debt Instrument [Line Items]
Number of credit facilities | credit_facility								2	2
Repayment of senior debt			$ 2,860,000,000	$ 3,073,000,000
Commercial paper [Member]
Debt Instrument [Line Items]
Total debt	$ 810,000,000	$ 810,000,000	810,000,000					$ 168,000,000
Weighted average commercial paper outstanding		$ 309,000,000	$ 328,000,000
Weighted-average interest rates (as a percent)		0.51%	0.49%
4.750% Senior Notes Due May 2045 [Member] | Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Face amount of debt						$ 600,000,000
Debt interest rate percentage						4.75%
3.50% debt securities due September 2015 [Member] | Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt interest rate percentage	3.50%	3.50%	3.50%		3.50%
Repayment of senior debt	$ 600,000,000
Domestic Line of Credit [Member] | 2017 Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity								400,000,000
Foreign Line of Credit [Member] | 2015 Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity								$ 792,000,000	€ 650,000,000
Foreign Line of Credit [Member] | 2020 Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							$ 900,000,000
Commercial paper [Member] | US Commercial Paper Program [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 900,000,000	$ 900,000,000	$ 900,000,000
Commercial paper [Member] | European Multi Currency Paper Program [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity | €					€ 300,000,000