Segment Information - Revenues and Operating Margin (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenues	$ 3,415.9	$ 1,523.5	$ 7,048.7	$ 3,572.4
Operating margin	522.1	479.5	1,147.6	1,145.5
Sales of Commodities [Member]
Revenues:
Revenues	3,091.6	1,280.6	6,459.3	3,060.2
Fees from Midstream Services [Member]
Revenues:
Revenues	324.3	242.9	589.4	512.2
Gathering and Processing [Member]
Revenues:
Revenues	1,504.4	634.2	2,737.6	1,441.2
Operating margin	301.2	237.2	576.6	492.8
Logistics And Transportation [Member]
Revenues:
Revenues	3,267.3	1,322.6	6,727.2	2,957.8
Operating margin	291.4	231.5	640.1	525.5
Other [Member]
Revenues:
Revenues	(70.5)	10.8	(69.1)	127.2
Operating margin	(70.5)	10.8	(69.1)	127.2
Corporate and Eliminations [Member]
Revenues:
Revenues	(1,285.3)	(444.1)	(2,347.0)	(953.8)
Operating Segments [Member]
Revenues:
Revenues	3,415.9	1,523.5	7,048.7	3,572.4
Operating Segments [Member] | Sales of Commodities [Member]
Revenues:
Revenues	3,091.6	1,280.6	6,459.3	3,060.2
Operating Segments [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues	324.3	242.9	589.4	512.2
Operating Segments [Member] | Gathering and Processing [Member]
Revenues:
Revenues	319.1	243.5	581.1	605.5
Operating Segments [Member] | Gathering and Processing [Member] | Sales of Commodities [Member]
Revenues:
Revenues	147.3	133.5	289.8	377.3
Operating Segments [Member] | Gathering and Processing [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues	171.8	110.0	291.3	228.2
Operating Segments [Member] | Logistics And Transportation [Member]
Revenues:
Revenues	3,167.3	1,269.2	6,536.7	2,839.7
Operating Segments [Member] | Logistics And Transportation [Member] | Sales of Commodities [Member]
Revenues:
Revenues	3,014.8	1,136.3	6,238.6	2,555.7
Operating Segments [Member] | Logistics And Transportation [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues	152.5	132.9	298.1	284.0
Operating Segments [Member] | Other [Member]
Revenues:
Revenues	(70.5)	10.8	(69.1)	127.2
Operating Segments [Member] | Other [Member] | Sales of Commodities [Member]
Revenues:
Revenues	(70.5)	10.8	(69.1)	127.2
Intersegment Eliminations [Member] | Gathering and Processing [Member]
Revenues:
Revenues	1,185.3	390.7	2,156.5	835.7
Intersegment Eliminations [Member] | Gathering and Processing [Member] | Sales of Commodities [Member]
Revenues:
Revenues	1,184.7	389.2	2,154.4	832.4
Intersegment Eliminations [Member] | Gathering and Processing [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues	0.6	1.5	2.1	3.3
Intersegment Eliminations [Member] | Logistics And Transportation [Member]
Revenues:
Revenues	100.0	53.4	190.5	118.1
Intersegment Eliminations [Member] | Logistics And Transportation [Member] | Sales of Commodities [Member]
Revenues:
Revenues	92.6	46.1	175.2	102.7
Intersegment Eliminations [Member] | Logistics And Transportation [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues	7.4	7.3	15.3	15.4
Intersegment Eliminations [Member] | Corporate and Eliminations [Member]
Revenues:
Revenues	(1,285.3)	(444.1)	(2,347.0)	(953.8)
Intersegment Eliminations [Member] | Corporate and Eliminations [Member] | Sales of Commodities [Member]
Revenues:
Revenues	(1,277.3)	(435.3)	(2,329.6)	(935.1)
Intersegment Eliminations [Member] | Corporate and Eliminations [Member] | Fees from Midstream Services [Member]
Revenues:
Revenues	$ (8.0)	$ (8.8)	$ (17.4)	$ (18.7)