Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 1	$ 1
Variable interest entities - assets	248	242
Variable interest entities - liabilities	$ 218	$ 217
Common stock, par value (per share)	$ 0.01	$ 0.01
Common stock, authorized shares	6,000,000,000	6,000,000,000
Common stock, issued shares	239,590,752	201,290,458
Common stock, outstanding shares	239,388,083	201,198,381

Amount of allowance for credit loss on accounts receivable.

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Face amount or stated value per share of common stock.

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