Equity (Unrecognized Compensation Expense Related to Stock-Based Compensation) (Details) $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense	$ 2
Weighted Average Period	1 year 6 months 25 days
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense	$ 28
Weighted Average Period	1 year 7 months 20 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense	$ 38
Weighted Average Period	1 year 9 months 3 days

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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