Fair Value (Tables)

6 Months Ended

Mar. 30, 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 March 30, 2018								As of September 29, 2017
			Fair Value Measurements								Fair Value Measurements
	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Assets
Money market funds	$	688.2	$	688.2	$	—	$	—	$	592.6	$	592.6	$	—	$	—
Total	$	688.2	$	688.2	$	—	$	—	$	592.6	$	592.6	$	—	$	—
Liabilities
Contingent consideration liability recorded for business combinations	$	9.1	$	—	$	—	$	9.1	$	11.9	$	—	$	—	$	11.9
Total	$	9.1	$	—	$	—	$	9.1	$	11.9	$	—	$	—	$	11.9

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

The following table summarizes changes to the fair value of the Level 3 liabilities (in millions):

	Contingent consideration
Balance as of September 29, 2017	$	11.9
Decreases to contingent consideration liability recorded for business combinations	(2.8		)
Balance as of March 30, 2018	$	9.1