CAPITAL STOCK - Description of Stock Based Compensation Plans and Related Costs (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Stock-settled and cash-settled compensation expensed	$ 110	$ 157	$ 142
Stock-settled and cash-settled compensation capitalized	28	37	41
Total stock-settled and cash-settled compensation costs	$ 138	$ 194	$ 183

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

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