Employee Incentive Plans - Amounts Recognized in Consolidated Financial Statements (Details) $ in Millions		12 Months Ended
	Jan. 25, 2019	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Allocation
Common units conversion ratio	1.15
Compensation expense		$ 39.4	$ 41.1	$ 48.1
Amount of related income tax benefit recognized in net income		9.1	5.3	11.3
Cost of unit-based compensation charged to general and administrative expense
Allocation
Compensation expense		32.7	30.3	37.4
Cost of unit-based compensation charged to operating expense
Allocation
Compensation expense		6.7	10.8	10.7
Non-controlling interest in unit-based compensation
Allocation
Compensation expense		$ 0.5	$ 15.7	$ 18.0