Arrangements With Off-Balance Sheet Risk (Narrative) (Details) $ in Millions	1 Months Ended		3 Months Ended
	Dec. 31, 2011 USD ($)	Jun. 30, 2011 USD ($)	Mar. 31, 2017 USD ($) satellites	Dec. 31, 2016 USD ($)
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			1,288
Revenues and cost of sales recorded under inventory supply agreement			1,500
Payments received under inventory supply agreement			1,740
Payments made under inventory supply agreement			48
Contributed Delta Program Launch Inventory [Member] | ULA [Member]
Guarantees [Line Items]
Maximum Potential Payments			72	$ 77
Contract Pricing [Member] | ULA [Member]
Guarantees [Line Items]
Maximum Potential Payments			261	261
Carrying Amount of Liabilities			$ 7	7
Indemnification Agreement [Member]
Guarantees [Line Items]
Number of satellite missions | satellites			3
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			196	216
Carrying Amount of Liabilities			5	5
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			29	29
Carrying Amount of Liabilities			$ 2	$ 2
Guarantor Obligations, Term			4
Maximum [Member] | Indemnification Agreement [Member]
Guarantees [Line Items]
Loss Contingency, Estimate of Possible Loss			$ 277