Segments - Revenue Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Revenue
Revenue	$ 17,730	$ 17,571
Business Segments
Revenue
Revenue	19,264	19,023
Other
Revenue
Other - divested businesses	1	18
Other revenue	21	44
Internal transactions
Revenue
Revenue	$ (1,557)	$ (1,514)

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details