Stock-Based Compensation (Performance Share Units) (Details) - USD ($) $ / shares in Units, $ 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]
Compensation expense	$ 30.1	$ 21.8	$ 24.3
Payout ratio for shares paid (as a percent)	100.00%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award service period	3 years
Compensation expense	$ 15.2	$ 6.9	$ 10.8
Weighted-average fair value of grants, per share (in usd per share)	$ 0	$ 237.68	$ 314.27
Payout ratio for shares paid (as a percent)	131.00%	126.00%	100.00%
Distributed (in shares)	(30,700)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 245.06
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0
Share-Based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Adjustments In Period, Weighted Average Grant Date Fair Value	$ 265.96
Share-Based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Adjustments In Period	17,800
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(5,400)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 270.84
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award service period	3 years
Compensation expense	$ 10.8	$ 11.0	$ 8.7
Weighted-average fair value of grants, per share (in usd per share)	$ 0	$ 240.87	$ 315.70
Distributed (in shares)	(39,900)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 275.58
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(8,800)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 272.57
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 4.1	$ 3.9	$ 4.8
Award expiration period	7 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(18,900)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 285.73