Segment Information, Other Financial Information (Details) - USD ($) $ in Millions |
3 Months Ended | ||||||||
---|---|---|---|---|---|---|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
Dec. 31, 2017 |
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Other financial information [Abstract] | |||||||||
Total assets | $ 14,753.2 | [1] | $ 13,653.8 | [2] | $ 14,388.6 | ||||
Goodwill | 256.6 | 369.0 | $ 256.6 | ||||||
Capital expenditures | 558.0 | 174.6 | |||||||
Operating Segments [Member] | Gathering and Processing [Member] | |||||||||
Other financial information [Abstract] | |||||||||
Total assets | 10,908.5 | [1] | 10,780.4 | [2] | |||||
Goodwill | 256.6 | 369.0 | |||||||
Capital expenditures | 273.2 | 139.2 | |||||||
Operating Segments [Member] | Logistics and Marketing [Member] | |||||||||
Other financial information [Abstract] | |||||||||
Total assets | 3,595.1 | [1] | 2,687.2 | [2] | |||||
Capital expenditures | 251.0 | 34.6 | |||||||
Operating Segments [Member] | Other Segment [Member] | |||||||||
Other financial information [Abstract] | |||||||||
Total assets | 103.0 | [1] | 44.9 | [2] | |||||
Operating Segments [Member] | Corporate and Eliminations [Member] | |||||||||
Other financial information [Abstract] | |||||||||
Total assets | 146.6 | [1] | 141.3 | [2] | |||||
Capital expenditures | $ 33.8 | $ 0.8 | |||||||
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