Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Details 5) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 53,500
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Explanation	We expect to recognize approximately 50 percent and 75 percent of our December 31, 2018 backlog as revenue over the next 12 and 24 months, respectively, with the remainder to be recognized thereafter.
Innovation Systems Net contract assets (liabilities)	$ 1,000
Unbilled Receivables, Current	5,026	$ 3,465
Amount of increase (decrease) in Unbilled Receivables	$ 1,561
Percent increase (decrease) in Unbilled Receivables	45.00%
Contract with Customer, Liability, Current	$ 1,917	1,761
Amount of decrease (increase) in Contract with Customer, Liability, Current	$ (156)
Percent decrease (increase) in Contract with Customer, Liability, Current	9.00%
Contract with Customer, Asset, Net, Current	$ 3,109	1,704
Amount of increase (decrease) in net contract assets (liabilities)	$ 1,405
Percent increase (decrease) in net contract assets (liabilities)	82.00%
Contract with Customer, Liability, Revenue Recognized	$ 1,300	$ 1,200	$ 1,300