Fair Value of Financial Instruments - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 24, 2023	Sep. 25, 2022	Sep. 26, 2021	Mar. 31, 2014
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value adjustment of warrants	$ 0.0	$ 0.1	$ 0.3
Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Term note	$ 455.7
TCT
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Percent ownership of voting common stock of TCT	0.70%
Total percent of voting common stock	8.70%
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments, fair value disclosure, total	$ 3.9
Level 3 | TCT and Private Equity Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Percent ownership of non-voting common stock	16.70%
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments, fair value disclosure, total	$ 1.7
Warrants	0.0	$ 0.1	$ 0.3	$ 16.9
Level 2 | Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	$ 392.2