Investment in Unconsolidated Affiliates Summarized Income Statement of Equity Method Investment (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 699.0	$ 928.0	$ 2,229.0	$ 2,481.0
Cost of natural gas and NGLs	263.0	516.0	958.0	1,335.0
Operating income	175.0	171.0	507.0	436.0
Net income	$ 123.0	$ 129.0	$ 351.0	$ 320.0

Equity Method Investment, Summarized Financial Information, Operating Income

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The amount of the cost of sales reported by an equity method investment of the entity.

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The amount of net income (loss) reported by an equity method investment of the entity.

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Amount of revenue from sale of product and rendering of service reported by equity method investee.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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