Segment Information - Revenues and Operating Margin (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues:
Revenues		$ 4,459.7	$ 2,115.1	$ 11,508.2	$ 5,687.5
Operating margin	[1]	655.6	630.0	1,803.1	1,775.6
Sales of Commodities [Member]
Revenues:
Revenues		4,118.1	1,840.8	10,577.3	4,900.8
Fees from Midstream Services [Member]
Revenues:
Revenues		341.6	274.3	930.9	786.7
Gathering and Processing [Member]
Revenues:
Revenues		2,148.1	875.5	4,886.1	2,316.6
Operating margin	[1]	361.4	261.0	938.2	753.7
Logistics And Transportation [Member]
Revenues:
Revenues		4,204.5	1,810.5	10,931.4	4,768.1
Operating margin	[1]	280.7	280.4	920.5	806.0
Other [Member]
Revenues:
Revenues		13.5	88.6	(55.6)	215.9
Operating margin	[1]	13.5	88.6	(55.6)	215.9
Corporate and Eliminations [Member]
Revenues:
Revenues		(1,906.4)	(659.5)	(4,253.7)	(1,613.1)
Operating Segments [Member]
Revenues:
Revenues		4,459.7	2,115.1	11,508.2	5,687.5
Operating Segments [Member] | Sales of Commodities [Member]
Revenues:
Revenues		4,118.1	1,840.8	10,577.3	4,900.8
Operating Segments [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues		341.6	274.3	930.9	786.7
Operating Segments [Member] | Gathering and Processing [Member]
Revenues:
Revenues		361.5	261.9	942.9	867.4
Operating Segments [Member] | Gathering and Processing [Member] | Sales of Commodities [Member]
Revenues:
Revenues		156.2	135.7	446.2	512.9
Operating Segments [Member] | Gathering and Processing [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues		205.3	126.2	496.7	354.5
Operating Segments [Member] | Logistics And Transportation [Member]
Revenues:
Revenues		4,084.7	1,764.6	10,620.9	4,604.2
Operating Segments [Member] | Logistics And Transportation [Member] | Sales of Commodities [Member]
Revenues:
Revenues		3,948.4	1,616.5	10,186.7	4,172.0
Operating Segments [Member] | Logistics And Transportation [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues		136.3	148.1	434.2	432.2
Operating Segments [Member] | Other [Member]
Revenues:
Revenues		13.5	88.6	(55.6)	215.9
Operating Segments [Member] | Other [Member] | Sales of Commodities [Member]
Revenues:
Revenues		13.5	88.6	(55.6)	215.9
Intersegment Eliminations [Member] | Gathering and Processing [Member]
Revenues:
Revenues		1,786.6	613.6	3,943.2	1,449.2
Intersegment Eliminations [Member] | Gathering and Processing [Member] | Sales of Commodities [Member]
Revenues:
Revenues		1,786.0	611.9	3,940.4	1,444.3
Intersegment Eliminations [Member] | Gathering and Processing [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues		0.6	1.7	2.8	4.9
Intersegment Eliminations [Member] | Logistics And Transportation [Member]
Revenues:
Revenues		119.8	45.9	310.5	163.9
Intersegment Eliminations [Member] | Logistics And Transportation [Member] | Sales of Commodities [Member]
Revenues:
Revenues		108.3	37.4	283.5	140.1
Intersegment Eliminations [Member] | Logistics And Transportation [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues		11.5	8.5	27.0	23.8
Intersegment Eliminations [Member] | Corporate and Eliminations [Member]
Revenues:
Revenues		(1,906.4)	(659.5)	(4,253.7)	(1,613.1)
Intersegment Eliminations [Member] | Corporate and Eliminations [Member] | Sales of Commodities [Member]
Revenues:
Revenues		(1,894.3)	(649.3)	(4,223.9)	(1,584.4)
Intersegment Eliminations [Member] | Corporate and Eliminations [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues		$ (12.1)	$ (10.2)	$ (29.8)	$ (28.7)

[1] Operating margin is calculated by subtracting Product purchases and fuel from Revenues.