Employee Incentive Plans - Amounts Recognized in Consolidated Financial Statements (Details) $ in Millions		12 Months Ended
	Jan. 25, 2019	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Allocation
Common units conversion ratio	1.15
Compensation expense		$ 28.4	$ 39.4	$ 41.1
Amount of related income tax benefit recognized in net income		6.7	9.1	5.3
Unvested restricted units
Allocation
Amount of related income tax benefit recognized in net income		6.0	2.2	0.7
Cost of unit-based compensation charged to general and administrative expense
Allocation
Compensation expense		21.3	32.7	30.3
Cost of unit-based compensation charged to operating expense
Allocation
Compensation expense		7.1	6.7	10.8
Non-controlling interest in unit-based compensation
Allocation
Compensation expense		$ 0.0	$ 0.5	$ 15.7