Fair Value (Tables)

3 Months Ended

Dec. 28, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis

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

	As of December 28, 2018								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*	$	1,085.7	$	1,084.7	$	1.0	$	—	$	79.3	$	29.7	$	49.6	$	—
U.S. Treasury and government securities	8.0		—		8.0		—		65.0		15.0		50.0		—
Corporate bonds and notes	1.4		—		1.4		—		216.0		—		216.0		—
Municipal bonds	4.8		—		4.8		—		2.8		—		2.8		—
Other government securities	1.9		—		1.9		—		33.1		—		33.1		—
Total	$	1,101.8	$	1,084.7	$	17.1	$	—	$	396.2	$	44.7	$	351.5	$	—
Liabilities
Contingent consideration	$	3.1	$	—	$	—	$	3.1	$	3.1	$	—	$	—	$	3.1
Total	$	3.1	$	—	$	—	$	3.1	$	3.1	$	—	$	—	$	3.1

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation