Equity (Stock-Based Compensation) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock-based compensation
Stock based compensation costs	$ 107	$ 100	$ 82
Tax benefits related to stock-based compensation arrangements	21	$ 17	$ 21
Unrecognized stock based compensation costs	$ 109
Unrecognized stock based compensation costs weighted-average period of recognition (in years)	1 year 8 months 12 days
Common stock authorized for awards (in shares)	60,000,000
Share-based Payment Arrangement [Member]
Stock-based compensation
Number of additional shares available for grant (in shares)	0

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

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