Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Share-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 10	$ 10	$ 19	$ 25
Cost not yet recognized, amount	72		$ 72
Cost not yet recognized, period for recognition			2 years
Performance-based Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 1
Stock granted (in shares)			1,323,267
Weighted average grant date fair value (in usd per share)			$ 11.34
Vesting period			1 year