Stock-Based Compensation - Supplemental Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-Based Compensation
Minimum tax withholdings	$ 9	$ 27	$ 36
Compensation Expense	27	27	32
Tax detriment/(benefit) recognized	2	(9)	(12)
Unrecognized Total Cost	41
RSUs
Stock-Based Compensation
Compensation Expense	9	9	9
Unrecognized Total Cost	$ 16
Weighted Average Recognition Period Remaining (In years)	1 year 9 months 18 days
Award vesting period	3 years
DSUs
Stock-Based Compensation
Compensation Expense	$ 2	2	2
Unrecognized Total Cost	$ 0
Weighted Average Recognition Period Remaining (In years)	0 years
RPSUs
Stock-Based Compensation
Compensation Expense	$ 9	10	10
Unrecognized Total Cost	$ 15
Weighted Average Recognition Period Remaining (In years)	1 year 2 months 8 days
Award vesting period	3 years
PRSUs
Stock-Based Compensation
Compensation Expense	$ 7	$ 6	$ 11
Unrecognized Total Cost	$ 10
Weighted Average Recognition Period Remaining (In years)	1 year 6 months 7 days
Award vesting period	3 years

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

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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