Fair Value (Tables)

12 Months Ended

Sep. 30, 2016

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 30, 2016								As of October 2, 2015
			Fair Value Measurements								Fair Value Measurements
	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Assets
Money market funds	$	408.7	$	408.7	$	—	$	—	$	464.6	$	464.6	$	—	$	—
Auction rate security	2.3		—		—		2.3		2.3		—		—		2.3
Foreign currency derivative assets	—		—		—		—		3.3		—		—		3.3
Total	$	411.0	$	408.7	$	—	$	2.3	$	470.2	$	464.6	$	—	$	5.6
Liabilities
Purchase obligation recorded for business combinations	$	—	$	—	$	—	$	—	$	75.4	$	—	$	—	$	75.4
Foreign currency derivative liabilities	—		—		—		—		2.8		—		—		2.8
Contingent consideration liability recorded for business combinations	7.9		—		—		7.9		0.5		—		—		0.5
Total	$	7.9	$	—	$	—	$	7.9	$	78.7	$	—	$	—	$	78.7

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

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

	Auction rate security		Foreign currency derivative
Balance as of October 2, 2015	$	2.3	$	3.3
Changes in fair value included in earnings	—		(3.3		)
Balance as of September 30, 2016	$	2.3	$	—

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):

	Purchase obligation			Foreign currency derivative			Contingent consideration
Balance as of October 2, 2015	$	75.4		$	2.8		$	0.5
Increases to Level 3 liabilities	—			—			7.4
Changes in fair value included in earnings	—			(2.8		)	—
Decreases of Level 3 liabilities	(75.4		)	—			—
Balance as of September 30, 2016	$	—		$	—		$	7.9