Arrangements With Off-Balance Sheet Risk (Narrative) (Details) - USD ($) $ in Millions		1 Months Ended
	Jul. 05, 2018	Dec. 31, 2011	Jun. 30, 2011	Sep. 30, 2018	Dec. 31, 2017
Guarantees [Line Items]
Additional potentially unrecoverable deferred production costs		$ 114	$ 271
Controlling Interest Ownership Percentage After Acquisition	80.00%
Payments to Acquire Interest in Joint Venture	$ 3,800
ULA [Member]
Guarantees [Line Items]
Delta launch program inventories included in contributed assets				$ 1,360
Delta launch program inventories subject to inventory supply agreement				1,860
ContributedInventoryNotYetConsumedbyJointVenture				327
Contributed Delta Program Launch Inventory [Member] | ULA [Member]
Guarantees [Line Items]
Maximum Potential Payments				52	$ 72
Contract Pricing [Member] | ULA [Member]
Guarantees [Line Items]
Maximum Potential Payments				261	261
Carrying Amount of Liabilities				7	7
Other Delta Contracts [Member] | Deferred support costs [Member]
Guarantees [Line Items]
Maximum Potential Payments				85
Other Delta Contracts [Member] | Deferred production costs [Member]
Guarantees [Line Items]
Maximum Potential Payments				91
Other Delta Contracts [Member] | ULA [Member]
Guarantees [Line Items]
Maximum Potential Payments				176	191
Carrying Amount of Liabilities
Deferred Support and Production Costs [Member]
Guarantees [Line Items]
Loss Contingency, Estimate of Possible Loss				317
Credit Guarantee [Member]
Guarantees [Line Items]
Maximum Potential Payments				106	109
Carrying Amount of Liabilities				16	$ 16
Maximum [Member] | Indemnification Agreement [Member]
Guarantees [Line Items]
Loss Contingency, Estimate of Possible Loss				$ 280
Embraer [Member]
Guarantees [Line Items]
Investments Net Asset Value	$ 4,750