Debt (Details) In Millions, unless otherwise specified	3 Months Ended					3 Months Ended
	Mar. 31, 2013 Commercial paper USD ($)	Dec. 31, 2012 Commercial paper USD ($)	Mar. 29, 2013 4.250% Senior notes due 2042 USD ($)	Mar. 08, 2013 4.250% Senior notes due 2042 USD ($)	Dec. 31, 2012 4.250% Senior notes due 2042 USD ($)	Mar. 31, 2013 Euro Facility USD ($)	Mar. 31, 2013 Euro Facility EUR (€)	Mar. 31, 2013 Euro Facility GBP (£)
Debt Instrument
Total debt	$ 383	$ 50
Weighted average commercial paper outstanding	162
Weighted-average interest rates (as a percent)	0.40%
Credit facility amount outstanding						30		20
Credit facility term						5 years	5 years	5 years
Credit facility maximum borrowing amount						836	650
Face amount of debt			256	90
Stated interest rate			4.25%	4.25%
Short-term debt aggregate principal amount					$ 166