Revenue (Condensed Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Revenues [Abstract]
Receivables, gross	$ 11,412	$ 11,711
Less: Allowance for doubtful accounts	612	419
Receivables, net	10,800	11,292
Noncurrent receivables, net (included in other noncurrent assets, net)	1,323	1,337
Contract acquisition and fulfillment costs (included in other noncurrent assets, net)	1,078	1,083
Noncurrent deferred revenue (included in other noncurrent liabilities)	$ 894	$ 618