Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Dec. 27, 2025	Sep. 27, 2025	Dec. 28, 2024	Sep. 28, 2024	Dec. 27, 2025	Dec. 28, 2024
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	$ 780.8	$ 1,134.7	$ 895.9	$ 957.3	$ 1,134.7	$ 957.3
Other comprehensive gain (loss), net	0.3	0.1	(1.4)	2.3	0.4	0.9
Balance at the end of the period	846.6	780.8	872.3	895.9	846.6	872.3
Unrealized loss on available-for-sale securities is presented net of tax	0.0		0.0		0.0	0.0
Total
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	9.1	9.0	11.6	9.3	9.0	9.3
Other comprehensive gain (loss), net	0.3	0.1	(1.4)	2.3
Balance at the end of the period	9.4	9.1	10.2	11.6	9.4	10.2
Foreign Currency Translation Adjustments, Net of Tax
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	9.6	9.9	9.8	9.8	9.9	9.8
Other comprehensive gain (loss), net	0.0	(0.3)	(0.3)	0.0
Balance at the end of the period	9.6	9.6	9.5	9.8	9.6	9.5
Defined Benefit Obligations, Net of Tax
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	(1.6)	(1.6)	0.7	0.7	(1.6)	0.7
Other comprehensive gain (loss), net	0.0	0.0	0.0	0.0
Balance at the end of the period	(1.6)	(1.6)	0.7	0.7	(1.6)	0.7
Unrealized Gain (Loss) on Available-for-sale Securities, Net of Tax
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	1.1	0.7	1.1	(1.2)	0.7	(1.2)
Other comprehensive gain (loss), net	0.3	0.4	(1.1)	2.3
Balance at the end of the period	$ 1.4	$ 1.1	$ 0.0	$ 1.1	$ 1.4	$ 0.0