Arrangements With Off-Balance Sheet Risk (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended
	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2019	Dec. 31, 2018
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			$ 4,200
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
Contributed Delta Program Launch Inventory [Member] | ULA [Member]
Guarantees [Line Items]
Maximum Potential Payments			35	$ 52
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	176
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	106
Carrying Amount of Liabilities			$ 30	$ 16