Incentive Program (Grant Value Of Restricted Stock Units) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant price, per share	$ 41.15	$ 68.77	$ 77.66
Units settled in stock	$ 325	$ 559	$ 620
Units settled in cash	32	55	61
Total value	$ 357	$ 614	$ 681

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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 (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Value, after forfeiture, of shares granted under share-based payment arrangement. Excludes employee stock ownership plan (ESOP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 30
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=116855757&loc=d3e3913-113898

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 30
-Section 35
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116859318&loc=d3e15009-113911

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- Definition

Share based compensation arrangement by share based payment award restricted stock and units settled in stock.

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- Definition

Share Based Compensation Arrangements By Share Based Payment Units Settled In Cash

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