Revenue from Contract With Customers - Performance domain (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) contract
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment term	1 year
Aerospace
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Sales expected to be recognized on multi-year contracts in place as of the end of the period | $	$ 1,639
Number of types of long-term sales contracts utilized | contract	2
Aerospace | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment term	1 year