Capital Stock (Summary Of Stock Option Activity) (Details) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Number of Shares
Outstanding at beginning of period, Number of Shares | shares	6.0
Granted, Number of Shares | shares	1.4
Exercised, Number of Shares | shares	(1.5)
Forfeited or expired, Number of Shares | shares	(0.3)
Outstanding at end of period, Number of Shares | shares	5.6
Exercisable at end of period, Number of Shares | shares	3.7
Weighted-Average Option Price per Share
Outstanding at beginning of period, Weighted-Average Option Price per Share | $ / shares	$ 87.23
Granted, Weighted-Average Option Price per Share | $ / shares	131.84
Exercised, Weighted-Average Option Price per Share | $ / shares	64.39
Forfeited or expired, Weighted-Average Option Price per Share | $ / shares	118.58
Outstanding at end of period, Weighted-Average Option Price per Share | $ / shares	102.80
Exercisable at end of period, Weighted-Average Option Price per Share | $ / shares	$ 88.04
Outstanding at end of period, Weighted-Average Remaining Contractual Life	5 years 2 months 7 days
Exercisable at end of period, Weighted-Average Remaining Contractual Life	3 years 7 months 12 days
Outstanding at end of period, Aggregate Intrinsic Value | $	$ 234.0
Exercisable at end of period, Aggregate Intrinsic Value | $	$ 207.8