The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

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Other Matters - Sale of Interest in Glass Mountain Pipeline, LLC (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Jun. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Ownership interest		50.00%
Glass Mountain Pipeline, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Proceeds from sale of interest in equity method investee	$ 292.1
Gain on sale of interest in equity method investee	$ 108.6
Glass Mountain Pipeline, LLC \| Operating segment \| Crude oil logistics
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Ownership interest			50.00%