Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-Based Compensation
Stock-based compensation expense	$ 12.9	$ 10.5	$ 10.6
Income tax benefit	$ 2.7	$ 2.2	$ 2.2
Minimum
Stock-Based Compensation
Sum of age and years of service for accelerated vesting on retirement of certain stock options and restricted stock awards	75 years
Stock Options
Stock-Based Compensation
Vesting period	3 years