Fair Value (Tables)

12 Months Ended

Sep. 27, 2019

Fair Value Disclosures [Abstract]

Fair Value, Assets Measured on Recurring Basis

Assets and liabilities recorded at fair value on a recurring basis consisted of the following (in millions):         

	As of September 27, 2019								As of September 28, 2018
			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*	$	851.3	$	809.5	$	41.8	$	—	$	733.3	$	683.7	$	49.6	$	—
U.S. Treasury and government securities	54.2		28.4		25.8		—		65.0		15.0		50.0		—
Corporate bonds and notes	72.1		—		72.1		—		216.0		—		216.0		—
Municipal bonds	104.6		—		104.6		—		2.8		—		2.8		—
Other government securities	—		—		—		—		33.1		—		33.1		—
Total	$	1,082.2	$	837.9	$	244.3	$	—	$	1,050.2	$	698.7	$	351.5	$	—
Liabilities
Contingent consideration	$	—	$	—	$	—	$	—	$	3.1	$	—	$	—	$	3.1
Total	$	—	$	—	$	—	$	—	$	3.1	$	—	$	—	$	3.1

* Cash equivalents included in Levels 1 and 2 consist of money market funds and corporate bonds and notes, foreign government bonds, commercial paper, and agency securities purchased with less than ninety days until maturity.