Basis of Presentation (Unaudited) (Details 2) $ in Billions	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation	$ 42.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Explanation	We expect to recognize approximately 50 percent and 75 percent of our March 31, 2018 backlog as revenue over the next 12 and 24 months, respectively, with the remainder to be recognized thereafter.