Consolidated Entities and Equity Method Investments - Investment in SNG (Details) - SNG(a) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement Information
Revenues	$ 152	$ 145	$ 473	$ 451
Operating income	82	71	274	230
Net income	$ 60	$ 58	$ 208	$ 190

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

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