Contract Asset and Liability (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Revenue from contract with customer [Line Items]
Contract with Customer, Asset, Change	$ 304
Contract with Customer, Liability, Change	(26)
Contract with Customer, Liability, Revenue Recognized	2,200
Contract with Customer, Asset, Allowance for Credit Loss	58
Contract assets, current	4,549	$ 4,184
Contract with Customer, Asset, Net, Noncurrent	1,277	1,338
Contract with Customer, Asset	5,826	5,522
Contract liabilities, current	6,384	6,180
Contract with Customer, Liability, Noncurrent	5,554	5,732
Contract with Customer, Liability	11,938	11,912
Contract with Customer, Net	6,112	$ 6,390
COVID-19 [Member]
Revenue from contract with customer [Line Items]
Contract with Customer, Asset, Allowance for Credit Loss	29
Otis [Member]
Revenue from contract with customer [Line Items]
Customer billings in excess of revenue recognized	$ 278