Segment information - Schedule of Reconciliation of Operating Profit (Loss) from Segments to Consolidated (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended		12 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Revenues:
Revenue		$ 231.1	$ 293.8		$ 594.2	$ 848.9
Cost of sales reportable segments:
Cost of goods and services sold	[1]	85.9	122.6		241.3	563.3
Segment, Reconciliation of Other Items from Segments to Consolidated [Abstract]
Amortization of intangible assets		(16.3)	(16.3)		(48.8)	(48.8)
Changes in fair value of financial instruments					0.0	(0.6)
Impairment of long-lived assets		0.0	0.0	$ (27.2)	0.0	(27.2)	$ (27.2)
Research and development		(13.5)	(13.8)		(41.1)	(61.6)
Selling, general and administrative		(38.9)	(76.6)		(135.0)	(247.2)
Interest expense		(15.2)	(8.3)		(44.6)	(56.2)
Gain (loss) on sale of business and assets held for sale		0.0	64.3		(12.2)	24.3
Other, net		(3.7)	21.9		62.3	15.8
Income (loss) before income taxes		57.6	142.4		133.5	(115.3)
Restructuring costs		0.3	6.3		(2.1)	22.9
Operating Segments
Revenues:
Revenue		217.4	269.5		545.2	726.8
Cost of sales reportable segments:
Cost of goods and services sold		80.5	95.1		216.6	290.7
Segment adjusted gross margin reportable segments:		136.9	174.4		328.6	436.1
Segment, Reconciliation of Other Items from Segments to Consolidated [Abstract]
All other revenues less other costs of revenue		8.5	2.9		25.3	(141.2)
Amortization of intangible assets		(16.3)	(16.3)		(48.8)	(48.8)
Restructuring costs		(0.2)	(4.9)		0.8	(7.5)
Inventory step-up provision		0.0	(1.2)		(1.8)	(1.2)
Changes in fair value of financial instruments		0.0	0.0		0.0	(0.6)
Impairment of long-lived assets		0.0	0.0		0.0	(27.2)
Research and development		(13.5)	(13.8)		(41.1)	(61.6)
Selling, general and administrative		(38.9)	(76.6)		(135.0)	(247.2)
Interest expense		(15.2)	(8.3)		(44.6)	(56.2)
Gain (loss) on sale of business and assets held for sale		0.0	64.3		(12.2)	24.3
Other, net		(3.7)	21.9		62.3	15.8
Income (loss) before income taxes		57.6	142.4		133.5	(115.3)
Restructuring costs		0.2	5.0		(1.0)	7.8
All other revenues
Revenues:
Revenue		13.7	24.3		49.0	122.1
Commercial Products | Operating Segments
Revenues:
Revenue		74.9	95.3		187.7	333.8
Cost of sales reportable segments:
Cost of goods and services sold		42.6	47.2		103.3	152.7
Segment adjusted gross margin reportable segments:		32.3	48.1		84.4	181.1
Segment, Reconciliation of Other Items from Segments to Consolidated [Abstract]
Restructuring costs		0.0			0.2
MCM Products | Operating Segments
Revenues:
Revenue		142.5	174.2		357.5	393.0
Cost of sales reportable segments:
Cost of goods and services sold		37.9	47.9		113.3	138.0
Segment adjusted gross margin reportable segments:		104.6	126.3		244.2	255.0
Segment, Reconciliation of Other Items from Segments to Consolidated [Abstract]
Restructuring costs		(0.2)	(4.9)		0.8	(7.5)
Inventory step-up provision			(1.2)		(1.8)	(1.2)
Changes in fair value of financial instruments						(0.6)
Restructuring costs		$ 0.2	$ 4.9		$ (1.0)	$ 7.5

[1] (1) Exclusive of intangible asset amortization