Employee Incentive Plans - Amounts Recognized in Consolidated Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Allocation
Total unit-based compensation expense	$ 5.7	$ 11.4	$ 14.2	$ 23.7
Amount of related income tax benefit recognized in net income	1.3	2.7	3.3	5.6
Cost of unit-based compensation charged to operating expense
Allocation
Total unit-based compensation expense	1.1	1.3	2.7	4.1
Cost of unit-based compensation charged to general and administrative expense
Allocation
Total unit-based compensation expense	$ 4.6	$ 10.1	$ 11.5	$ 19.6