Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares)	49.1
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	2 years
Weighted average grant date fair value (in dollars per share)	$ 335.86	$ 234.93	$ 198.57
Shares issued in period (in shares)	0.5	0.7	0.7
Shares expected to be issued (in shares)	0.4
Total compensation cost not yet recognized	$ 111.6
Period for recognition of the compensation cost not yet recognized	12 months
Shareholder Value Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Weighted average grant date fair value (in dollars per share)	$ 349.63	$ 203.88	$ 230.19
Shares issued in period (in shares)	0.3	0.5	1.0
Shares expected to be issued (in shares)	0.2
Total compensation cost not yet recognized	$ 51.1
Period for recognition of the compensation cost not yet recognized	21 months
Relative Value Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Weighted average grant date fair value (in dollars per share)	$ 397.95	$ 230.00	$ 286.71
Shares issued in period (in shares)	0.1
Shares expected to be issued (in shares)	0.1
Total compensation cost not yet recognized	$ 21.1
Period for recognition of the compensation cost not yet recognized	22 months
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Weighted average grant date fair value (in dollars per share)	$ 339.30	$ 239.88	$ 196.30
Shares issued in period (in shares)	0.5	0.8	0.6
Shares expected to be issued (in shares)	0.4
Total compensation cost not yet recognized	$ 275.3
Period for recognition of the compensation cost not yet recognized	22 months
Grants in period (in shares)	1.0	1.0	0.7