Investments in Unconsolidated Affiliates - Equity Method Investment Summarized Financial Information, Statement of Operations (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity Method Investments and Joint Ventures [Abstract]
Operating revenue	$ 510	$ 432	$ 1,037	$ 853
Operating expenses	191	162	376	353
Net income	$ 318	$ 269	$ 659	$ 500

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

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