Summary of Significant Accounting Policies Update - Contracts accounted for under cumulative catch-up method (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Use of Estimates
Revenue recognized from performance obligations satisfied in prior periods	$ 55		$ 159
Cumulative catch-up method
Use of Estimates
Cumulative Catch-Up Adjustments	63	$ 5	167	$ 2
Change in Accounting Estimate Financial Effect Increase In Net Income	$ 48	$ 3	$ 127	$ 1
Change in Accounting Estimate Financial Effect Increase in Earnings Per Share Diluted	$ 0.19	$ 0.01	$ 0.49	$ 0.00
Gross favorable adjustments	$ 79	$ 20	$ 205	$ 63
Gross unfavorable adjustments	$ 16	$ 15	$ 38	$ 61