Partners' Capital and Distributions - Units Outstanding (Details) - shares	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019
Series A Preferred Units
Activity for preferred units and common units
Outstanding, beginning of period (units)	71,090,468	71,090,468	71,090,468	71,090,468
Outstanding, end of period (units)	71,090,468	71,090,468	71,090,468	71,090,468
Series B Preferred Units
Activity for preferred units and common units
Outstanding, beginning of period (units)	800,000	800,000	800,000	800,000
Outstanding, end of period (units)	800,000	800,000	800,000	800,000
Common Units
Activity for preferred units and common units
Outstanding, beginning of period (units)	728,053,007	728,028,576	726,785,813	726,361,924
Issuances of common units under equity-indexed compensation plans (units)	47,391	24,431	638,806	423,889
Outstanding, end of period (units)	728,100,398	728,053,007	727,424,619	726,785,813