Financial Instruments and Fair Value Measurements - Schedule of Carrying Amount and Fair Value of Long-term Debt (Details) - USD ($) $ in Millions	Sep. 26, 2025	Dec. 27, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Carrying Value	$ 3,754.2	$ 915.6
Fair Value	3,807.1	927.0
Level 1 | 8.50% Senior Secured Notes due April 2031
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Carrying Value	1,062.8	0.0
Fair Value	1,071.7	0.0
Level 1 | 14.75% Second-Out Takeback Notes due November 2028
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Carrying Value	0.0	505.4
Fair Value	0.0	511.6
Level 2 | Term Loan due July 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Carrying Value	1,200.0	0.0
Fair Value	1,242.0	0.0
Level 2 | Term Loan due April 2031
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Carrying Value	1,491.4	0.0
Fair Value	1,493.4	0.0
Level 2 | Second-Out Takeback Term Loan Due November 2028
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Carrying Value	0.0	410.2
Fair Value	$ 0.0	$ 415.4