Intangible assets and goodwill - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill
Balance at beginning of period	$ 2,374	$ 699
Impairment losses	(636)
Acquisitions		1,669
Disposal of immaterial subsidiary	(3)
Foreign currency translation	6	6
Balance at end of period	1,751	2,374
Neptec
Goodwill
Acquisitions	22
Space Systems
Goodwill
Balance at beginning of period	774	625
Impairment losses	(494)
Acquisitions		143
Foreign currency translation	6	6
Balance at end of period	296	774
Space Systems | MDA reporting unit
Goodwill
Impairment losses	(477)
Space Systems | SSL, Other reporting units
Goodwill
Impairment losses	(17)
Space Systems | Neptec
Goodwill
Acquisitions	22
Imagery
Goodwill
Balance at beginning of period	1,427	27
Impairment losses	(142)
Acquisitions		1,400
Balance at end of period	1,285	1,427
Services
Goodwill
Balance at beginning of period	173	47
Acquisitions		126
Disposal of immaterial subsidiary	(3)
Balance at end of period	$ 170	$ 173