Capital Stock (Summary of Share Repurchases) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		0 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Apr. 15, 2014 Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased	14.3	5.5	2.3
Average price per share	$ 88.14	$ 62.41	$ 98.03
Aggregate cost	$ 1,262.8	$ 340.2	$ 220.8
Authorization remaining at the end of each period	$ 2,428.2	$ 1,496.6	$ 2,207.4