Trade and other receivables - Expected timing of billing and collection of orbital receivables (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Trade and other receivables
Orbital receivables	$ 407	$ 424
Minimum
Trade and other receivables
Discount rate for recognition of revenue on percentage completion basis	6.00%
Maximum
Trade and other receivables
Discount rate for recognition of revenue on percentage completion basis	10.00%
Space Systems
Trade and other receivables
Impairment to long-term orbital receivables	$ 22