Employee Incentive Plans - Amounts Recognized in Consolidated Financial Statements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allocation
Compensation expense	$ 19.2	$ 30.4	$ 25.3
Amount of related income tax benefit recognized in net income	4.5	7.1	5.9
Cost of unit-based compensation charged to operating expense
Allocation
Compensation expense	3.7	5.7	6.6
Cost of unit-based compensation charged to general and administrative expense
Allocation
Compensation expense	$ 15.5	$ 24.7	$ 18.7