Segment Information - Other Financial Information (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Other financial information [Abstract]
Total assets		$ 15,965.4		$ 15,965.4		$ 18,815.1
Operating Segments [Member]
Other financial information [Abstract]
Total assets	[1]	15,965.4	$ 18,318.2	15,965.4	$ 18,318.2
Goodwill		45.2	46.6	45.2	46.6
Capital expenditures		169.6	857.1	473.8	1,762.6
Operating Segments [Member] | Gathering and Processing [Member]
Other financial information [Abstract]
Total assets	[1]	9,124.2	12,144.4	9,124.2	12,144.4
Goodwill		45.2	46.6	45.2	46.6
Capital expenditures		37.1	420.8	154.6	838.5
Operating Segments [Member] | Logistics and Transportation [Member]
Other financial information [Abstract]
Total assets	[1]	6,697.2	5,994.7	6,697.2	5,994.7
Capital expenditures		127.9	425.5	306.3	896.3
Operating Segments [Member] | Other [Member]
Other financial information [Abstract]
Total assets	[1]	22.0	19.0	22.0	19.0
Operating Segments [Member] | Corporate and Eliminations [Member]
Other financial information [Abstract]
Total assets	[1]	122.0	160.1	122.0	160.1
Capital expenditures		$ 4.6	$ 10.8	$ 12.9	$ 27.8

[1] Assets in the Corporate and Eliminations column primarily include tax-related assets, cash, prepaids and debt issuance costs for our revolving credit facilities.