Discontinued operations - Financial information Operations (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2020
Costs and expenses:
Income from operations of discontinued operations, net of tax		$ 32.0
Gain on disposal of discontinued operations, net of tax	$ 1.0	305.0
Income from discontinued operations, net of tax	1.0	337.0
MDA business | Discontinued operations
Revenues:
Total revenues		86.0
Costs and expenses:
Selling, general and administrative		13.0
Depreciation and amortization		4.0
Impairment loss		12.0
Operating loss		(5.0)
Interest expense, net		1.0
Other income, net		(34.0)
Income before taxes		28.0
Income tax benefit		(4.0)
Income from operations of discontinued operations, net of tax		32.0
Gain on disposal of discontinued operations, net of tax	1.0	305.0	$ 317.0
Income from discontinued operations, net of tax	$ 1.0	337.0
MDA business | Discontinued operations | Accrued Liabilities
Costs and expenses:
Recovery of previously recorded liability from dispute		39.0
MDA business | Discontinued operations | Product
Revenues:
Total revenues		44.0
Costs and expenses:
Costs, excluding depreciation and amortization		38.0
MDA business | Discontinued operations | Service
Revenues:
Total revenues		42.0
Costs and expenses:
Costs, excluding depreciation and amortization		$ 24.0