Capital Stock (Summary of Stock Option Activity) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period, Number of Shares	10.0
Granted, Number of Shares	1.8
Exercised, Number of Shares	(3.8)
Forfeited or expired, Number of Shares	(0.3)
Outstanding at end of period, Number of Shares	7.7
Exercisable at end of period, Number of Shares	5.2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding at beginning of period, Weighted-Average Option Price per Share	$ 65.38
Granted, Weighted-Average Option Price per Share	$ 90.31
Exercised, Weighted-Average Option Price per Share	$ 67.26
Forfeited or expired, Weighted-Average Option Price per Share	$ 68.46
Outstanding at end of period, Weighted-Average Option Price per Share	$ 70.15
Exercisable at end of period, Weighted-Average Option Price per Share	$ 65.95
Outstanding at end of period, Weighted-Average Remaining Contractual Life	3 years 8 months 19 days
Exercisable at end of period, Weighted-Average Remaining Contractual Life	2 years 7 months 28 days
Outstanding at end of period, Aggregate Intrinsic Value	$ 382.3
Exercisable at end of period, Aggregate Intrinsic Value	$ 278.7