Investments in Unconsolidated Affiliates - Equity Method Investment Summarized Financial Information, Statement of Operations (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Operating revenue	$ 527	$ 421
Operating expenses	185	191
Net income	$ 341	$ 231

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

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