Goodwill and Other Purchased Intangible Assets (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Amortization of Intangible Assets	$ 14	$ 16	$ 22
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	22 years
Finite-Lived Intangible Assets, Amortization Expense, Average Next Five Years	$ 10
Aerospace Systems [Member]
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	$ 570	$ 570