Employee Incentive Plans - Amounts Recognized in Consolidated Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Allocation
Total unit-based compensation expense	$ 4.5	$ 5.7	$ 8.5	$ 12.3
Amount of related income tax benefit recognized in net income	1.1	1.3	2.0	2.9
Cost of unit-based compensation charged to operating expense
Allocation
Total unit-based compensation expense	0.7	1.2	1.6	2.8
Cost of unit-based compensation charged to general and administrative expense
Allocation
Total unit-based compensation expense	$ 3.8	$ 4.5	$ 6.9	$ 9.5