Capital Stock (Summary of Stock Option Activity) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Options outstanding at January 1, 2013	19.7
Shares, Granted	3.1
Shares, Exercised	(5.0)
Shares, Cancelled	(0.8)
Shares, Options outstanding at December 31, 2013	17.0
Shares, Exercisable at December 31, 2013	10.1
Shares, Options expected to vest	6.5
Weighted average exercise price, Options outstanding at January 1, 2013	$ 52.23
Weighted average excercise price, Granted	$ 64.11
Weighted average exercise price, Exercised	$ 47.96
Weighted average exercise price, Cancelled	$ 57.75
Weighted average exercise price, Options outstanding at December 31, 2013	$ 55.35
Weighted average exercise price, Exercisable at December 31, 2013	$ 53.77
Weighted average exercise price, Options expected to vest	$ 57.47
Weighted-average remaining contractual term, Options outstanding at December 31, 2013	5 years 6 months
Weighted-average remaining contractual term, Exercisable at December 31, 2013	3 years 10 months 24 days
Weighted-average remaining contractual term, Options expected to vest	7 years 10 months 24 days
Aggregate intrinsic value, Options outstanding at December 31, 2013	$ 337.4
Aggregate intrinsic value, Exercisable at December 31, 2013	216.7
Aggregate intrinsic value, Options expected to vest	$ 114.0