Stock-Based Compensation - Stock Award Information and Fair Value Assumptions (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-based compensation
Unrecognized compensation cost related to stock options	$ 38.7
Stock-based compensation expense
Total stock-based compensation cost	31.5	$ 25.7	$ 24.8
Capitalized cost during the period	(4.5)	(1.9)	(4.5)
Amortization of capitalized cost during the period	4.7	1.2	6.7
Total stock-based compensation expense	31.7	25.0	27.0
Income tax benefit	11.4	$ 11.5	$ 19.1
Unrecognized compensation cost related to awards other than options	$ 38.7
Weighted average period of recognition of unrecognized compensation cost related to restricted stock awards	1 year 8 months 12 days
Executive Incentive Program
Stock-based compensation
Shares available for grant under the plan (in shares)	1,400
Restricted shares, performance shares, or other full value awards | Executive Incentive Program
Stock-based compensation
Shares available for grant under the plan (in shares)	600
Stock options - annual equity grant
Stock-based compensation
Stock options granted (in shares)	179
Weighted-average assumptions used to estimate grant date fair value of stock options
Expected dividend yield (as a percent)	1.20%	0.90%	1.40%
Expected life in years	4 years 7 months 6 days	4 years 8 months 12 days	4 years 10 months 24 days
Expected volatility (as a percent)	32.40%	29.10%	28.70%
Risk-free interest rate (as a percent)	3.60%	1.80%	0.40%
Weighted average grant date fair value (in dollars per share)	$ 74.20	$ 55.96	$ 32.51
Fair value of equity awards granted	$ 13.3	$ 12.8	$ 11.8
Restricted stock awards
Stock-based compensation
Awards granted (in shares)	50
Unrecognized compensation cost related to stock options	$ 8.6
Stock-based compensation expense
Total stock-based compensation cost	$ 8.3	7.2	6.7
Vesting period	3 years
Unrecognized compensation cost related to awards other than options	$ 8.6
Weighted average period of recognition of unrecognized compensation cost related to restricted stock awards	1 year 8 months 12 days
Performance share awards
Stock-based compensation
Awards granted (in shares)	35
Unrecognized compensation cost related to stock options	$ 10.2
Stock-based compensation expense
Total stock-based compensation cost	$ 8.8	8.3	6.9
Vesting period	3 years
Unrecognized compensation cost related to awards other than options	$ 10.2
Weighted average period of recognition of unrecognized compensation cost related to restricted stock awards	1 year 9 months 18 days
Q2 2022 Stock Option and Stock Appreciation Right Grant
Stock-based compensation expense
Total stock-based compensation cost	$ 6.7	2.9
Capitalized cost during the period	$ (0.5)	(0.7)
Q2 2018 Stock option and stock appreciation right grant
Stock-based compensation expense
Total stock-based compensation cost			4.6
Stock option awards
Stock-based compensation
Stock options granted (in shares)	179
Unrecognized compensation cost related to stock options	$ 17.5
Stock-based compensation expense
Total stock-based compensation cost	$ 14.4	$ 10.2	7.0
Vesting period	3 years
Maximum term life	10 years
Unrecognized compensation cost related to awards other than options	$ 17.5
2022 Broad-based Grant
Weighted-average assumptions used to estimate grant date fair value of stock options
Expected dividend yield (as a percent)		1.00%
Expected life in years		3 years 9 months 18 days
Expected volatility (as a percent)		31.90%
Risk-free interest rate (as a percent)		3.90%
Weighted average grant date fair value (in dollars per share)		$ 80.23
Fair value of equity awards granted		$ 40.4
Stock appreciation rights
Stock-based compensation expense
Total stock-based compensation cost	$ 0.0	$ 0.0	$ 4.2