Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
GT Advanced Technologies Inc
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Charged to Other Accounts			$ 22.0
Valuation Allowance of Deferred Tax Assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 152.4	$ 227.4	249.9
Charged (Credited) to Costs and Expenses	0.4	7.0	3.3
Charged to Other Accounts	0.2	(16.7)	8.7
Deductions/Write-offs	(2.7)	(65.3)	(34.5)
Balance at End of Period	$ 150.3	$ 152.4	$ 227.4