Fair Value (Tables)

12 Months Ended

Sep. 29, 2023

Fair Value Disclosures [Abstract]

Fair Value, Assets Measured on Recurring Basis

	As of September 29, 2023								As of September 30, 2022
			Fair Value Measurements								Fair Value Measurements
	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Assets
Cash and cash equivalents (1)	$	718.8	$	718.5	$	0.3	$	—	$	566.0	$	565.7	$	0.3	$	—
U.S. Treasury and government securities	19.2		—		19.2		—		13.6		3.6		10.0		—
Corporate bonds and notes	—		—		—		—		0.2		—		0.2		—
Municipal bonds	0.5		—		0.5		—		7.0		—		7.0		—
Total assets at fair value	$	738.5	$	718.5	$	20.0	$	—	$	586.8	$	569.3	$	17.5	$	—

(1) Cash equivalents included in Levels 1 and 2 consist of money market funds and corporate bonds and notes, US Treasury and government securities, and agency securities purchased with less than ninety days until maturity.

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments

The carrying amount and estimated fair value of debt under Senior Notes consists of the following (in millions):

	As of
	September 29, 2023				September 30, 2022
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
0.90% Senior Notes due 2023	$	—	$	—	$	499.2	$	488.5
1.80% Senior Notes due 2026	497.7		444.5		496.8		431.2
3.00% Senior Notes due 2031	495.2		390.4		494.5		377.6
Total debt under Senior Notes	$	992.9	$	834.9	$	1,490.5	$	1,297.3