Revenue Recognition Revenue Recognition (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract assets, current	$ 4,334	$ 3,486
Contract with Customer, Asset, Net, Noncurrent	1,215	1,142
Contract with Customer, Asset	5,549	4,628
Contract liabilities, current	6,219	5,720
Contract with Customer, Liability, Noncurrent	5,190	5,069
Contract with Customer, Liability	11,409	10,789
Contract with Customer, Net	5,860	6,161
Contract with Customer, Liability, Revenue Recognized	3,200
Capitalized Contract Cost, Net	1,229	914
Revenue, Remaining Performance Obligation, Amount	$ 125,100	$ 115,500
Revenue, Remaining Performance Obligations, to be recognized within 24 months	45.00%
Contract with Customer, Asset, Change	$ 921
Contract with Customer, Liability, Change	$ 620