Valuation And Qualifying Accounts (Allowance For Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Credit Loss
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 1,235	$ 907	$ 663
Charged to Costs and Expenses	1,972	2,575	1,791
Charged to Other Accounts	405	0	0
Acquisitions	0	0	179
Deductions	2,023	2,247	1,726
Balance at End of Period (e)	1,589	1,235	907
Allowance for Deferred Tax Assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	4,941	4,588	4,640
Charged to Costs and Expenses	(168)	(18)	(210)
Charged to Other Accounts	0	371	(53)
Acquisitions	0	0	211
Deductions	0	0	0
Balance at End of Period (e)	$ 4,773	$ 4,941	$ 4,588

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of valuation and qualifying accounts and reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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- Definition

Amount of increase in valuation and qualifying accounts and reserves from charge to cost and expense.

+ References

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- Definition

Amount of increase in valuation and qualifying accounts and reserves from charge to accounts other than cost and expense.

+ References

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Amount of decrease in valuation and qualifying accounts and reserves.

+ References

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- Definition

Amount of increase in valuation and qualifying accounts and reserves from business combination.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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