Segments - Revenue Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenue
Revenue	$ 17,571	$ 18,182	$ 77,000
Business Segments
Revenue
Revenue	19,023	19,398
Other
Revenue
Other - divested businesses	18	377
Other revenue	44	74
Internal transactions
Revenue
Revenue	$ (1,514)	$ (1,668)

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process, excluding amounts attributable to disposal groups.

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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).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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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