Discontinued operations - Financial information Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Costs and expenses:
Income (loss) from operations of discontinued operations, net of tax	$ 32	$ 26	$ (377)
Gain on disposal of discontinued operations, net of tax	317
Income (loss) from discontinued operations, net of tax	349	26	(377)
MDA business | Discontinued operations
Revenues:
Total revenues	86	367	420
Costs and expenses:
Selling, general and administrative	13	88	59
Depreciation and amortization	4	11	10
Impairment loss	12	12	477
Operating (loss) income	(5)	23	(389)
Interest expense, net	1	1	1
Other (income) expense, net	(34)	3
Income before taxes	28	19	(390)
Income tax benefit	(4)	(7)	(13)
Income (loss) from operations of discontinued operations, net of tax	32	26	(377)
Gain on disposal of discontinued operations, net of tax	317
Income (loss) from discontinued operations, net of tax	349	26	(377)
Goodwill impairment	0		477
Investment impairment loss	0	12	0
MDA business | Discontinued operations | Product
Revenues:
Total revenues	44	206	238
Costs and expenses:
Costs, excluding depreciation and amortization	38	149	149
MDA business | Discontinued operations | Service
Revenues:
Total revenues	42	161	182
Costs and expenses:
Costs, excluding depreciation and amortization	$ 24	$ 84	$ 114