Investments (Tables)

12 Months Ended

Sep. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments

Our investments consist of (in millions):

	September 30,
	2018			2017
Fixed income securities	$	419.0		$	1,387.6
Equity securities	1,090.0			—
Other	69.9			62.7
Total investments	1,578.9			1,450.3
Less short-term investments	(290.9		)	(1,124.6		)
Long-term investments	$	1,288.0		$	325.7

Schedule of Available-for-sale Investments

These investments were included in the following line items within the Consolidated Balance Sheet (in millions):

	September 30,
	2018		2017
Short-term investments	$	290.9	$	1,124.6
Long-term investments	128.1		263.0
Total	$	419.0	$	1,387.6

Our available-for-sale investments consist of (in millions):

	September 30,
	2018		2017
Certificates of deposit and time deposits	$	169.6	$	1,005.3
Commercial paper	—		20.3
Corporate debt securities	158.4		199.4
Government securities	65.8		116.8
Asset-backed securities	25.2		45.8
Total	$	419.0	$	1,387.6

Schedule of Contractual Maturities of Investments

The table below summarizes the contractual maturities of our investments as of September 30, 2018 (in millions). Actual maturities may differ from the contractual maturities below as borrowers may have the right to prepay certain obligations.

	Fair Value
Less than one year	$	290.9
Due in one to five years	128.1
Total	$	419.0

Schedule of Fair Value of Investments

Fair values of our investments were (in millions):

	September 30, 2018
	Level 1		Level 2		Level 3		Total
Certificates of deposit and time deposits	$	—	$	169.6	$	—	$	169.6
Corporate debt securities	—		158.4		—		158.4
Government securities	55.7		10.1		—		65.8
Asset-backed securities	—		25.2		—		25.2
Equity securities	—		—		1,090.0		1,090.0
Total	$	55.7	$	363.3	$	1,090.0	$	1,509.0

	September 30, 2017
	Level 1		Level 2		Level 3		Total
Certificates of deposit and time deposits	$	—	$	1,005.3	$	—	$	1,005.3
Commercial paper	—		20.3		—		20.3
Corporate debt securities	—		199.4		—		199.4
Government securities	98.9		17.9		—		116.8
Asset-backed securities	—		45.8		—		45.8
Total	$	98.9	$	1,288.7	$	—	$	1,387.6

Summary of Changes in the Fair Value of Level 3 Investments

The table below sets forth a summary of changes in the fair value of our Level 3 investments (in millions):

	Equity Securities
PTC Share purchase July 19, 2018	$	954.9
Unrealized gain	135.1
Balance September 30, 2018	$	1,090.0