Discontinued operations - Financial information Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Costs and expenses:
Income from operations of discontinued operations, net of tax	$ 2	$ 9	$ 32	$ 20
Gain on disposal of discontinued operations, net of tax	304		304
Income from discontinued operations, net of tax	306	9	336	20
MDA business | Discontinued operations
Revenues:
Total revenues	11	97	86	193
Costs and expenses:
Selling, general and administrative		13	13	31
Depreciation and amortization		3	4	6
Impairment loss	0	12	12	12
Operating (loss) income	4	9	(5)	19
Interest expense, net			1
Other (income) expense, net	2	(1)	(34)
Income before taxes	2	10	28	19
Income tax expense (benefit)		1	(4)	(1)
Income from operations of discontinued operations, net of tax	2	9	32	20
Gain on disposal of discontinued operations, net of tax	304		304
Income from discontinued operations, net of tax	306	9	336	20
MDA business | Discontinued operations | Product
Revenues:
Total revenues	5	57	44	110
Costs and expenses:
Costs, excluding depreciation and amortization	4	39	38	80
MDA business | Discontinued operations | Service
Revenues:
Total revenues	6	40	42	83
Costs and expenses:
Costs, excluding depreciation and amortization	$ 3	$ 21	$ 24	$ 45