Arrangements With Off-Balance Sheet Risk (Narrative) (Details) $ in Millions	1 Months Ended		9 Months Ended
	Dec. 31, 2011 USD ($)	Jun. 30, 2011 USD ($)	Sep. 30, 2015 USD ($) satellites	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Guarantees [Line Items]
Number of satellite missions | satellites			4
Additional potentially unrecoverable deferred production costs	$ 114	$ 271
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 launch program inventories consumed by ULA			1,253
Revenues and cost of sales recorded under inventory supply agreement			1,352
Payments received under inventory supply agreement			1,740
Payments made under inventory supply agreement			71
Contributed Delta Program Launch Inventory [Member] | ULA [Member]
Guarantees [Line Items]
Maximum Potential Payments			107		$ 114
Indemnification Agreement [Member]
Guarantees [Line Items]
Maximum exposure to loss			$ 278
Number of satellite missions | satellites			3
Indemnification Agreement [Member] | Indemnification Payment [Member]
Guarantees [Line Items]
Maximum exposure to loss			$ 261
Other Delta Contracts [Member] | Deferred support costs [Member]
Guarantees [Line Items]
Maximum Potential Payments			85
Other Delta Contracts [Member] | ULA [Member]
Guarantees [Line Items]
Maximum Potential Payments			231		$ 150
Carrying Amount of Liabilities			5
Deferred Support and Production Costs [Member]
Guarantees [Line Items]
Loss Contingency, Estimate of Possible Loss			$ 317
Other Indemnifications [Member]
Guarantees [Line Items]
Maximum Potential Payments				$ 44	$ 63
Carrying Amount of Liabilities				$ 12	20
Guarantor Obligations, Payment			$ 12
Credit Guarantee [Member]
Guarantees [Line Items]
Maximum Potential Payments			30		30
Carrying Amount of Liabilities			$ 2		$ 2
Guarantor Obligations, Term			6