Capital Stock (Summary of Stock Option Activity) (Details) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Options outstanding at January 1 (in shares) | shares	12.2
Shares, Granted (in shares) | shares	1.8
Shares, Exercised (in shares) | shares	(1.6)
Shares, Cancelled or forfeited (in shares) | shares	(0.3)
Shares, Options outstanding at December 31 (in shares) | shares	12.1
Shares, Exercisable at December 31 (in shares) | shares	7.1
Shares, Options expected to vest (in shares) | shares	4.6
Weighted Average Exercise Price
Weighted average exercise price, Options outstanding at January 1 (in dollars per share) | $ / shares	$ 131.72
Weighted average exercise price, Granted (in dollars per share) | $ / shares	235.35
Weighted average exercise price, Exercised (in dollars per share) | $ / shares	96.41
Weighted average exercise price, Cancelled or forfeited (in dollars per share) | $ / shares	192.60
Weighted average exercise price, Options outstanding at December 31 (in dollars per share) | $ / shares	150.17
Weighted average exercise price, Exercisable at December 31 (in dollars per share) | $ / shares	113.56
Weighted average exercise price, Options expected to vest (in dollars per share) | $ / shares	$ 199.41
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average remaining contractual term, Options outstanding at December 31 (in years)	5 years 8 months 12 days
Weighted-average remaining contractual term, Exercisable at December 31 (in years)	4 years 2 months 12 days
Weighted-average remaining contractual term, Options expected to vest (in years)	7 years 8 months 12 days
Aggregate intrinsic value, Options outstanding at December 31 | $	$ 1,424.2
Aggregate intrinsic value, Exercisable at December 31 | $	1,086.3
Aggregate intrinsic value, Options expected to vest | $	$ 313.3