Basis Of Presentation (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Jan. 01, 2016
Basis of Presentation [Line Items]
Change in diluted earnings per share due to net favorable/(unfavorable) cumulative catch-up adjustments	$ (0.35)	$ (0.11)	$ (0.05)	$ (0.95)
Increase/(Decrease) in Earnings from operations due to change in accounting estimate	$ (302,000,000)	$ (69,000,000)	$ (39,000,000)	$ (656,000,000)
Pro Forma [Member] | Retained Earnings [Member]
Basis of Presentation [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets						$ 1,000
Pro Forma [Member] | Sales Revenue, Net [Member]
Basis of Presentation [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets						10,000
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					$ 1,000
Pro Forma [Member] | Operating Income (Loss) [Member]
Basis of Presentation [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets						$ 1,000
Assets [Member] | Pro Forma [Member]
Basis of Presentation [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					20,000
Defense Contracts [Member] | Pro Forma [Member] | Sales Revenue, Net [Member]
Basis of Presentation [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					2,000
Operating Segments [Member] | Pro Forma [Member] | Operating Income (Loss) [Member]
Basis of Presentation [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					$ 400