Fair Value Measurements (Tables)

12 Months Ended

Mar. 31, 2019

Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings [Abstract]

Summary of Assets Measured at Fair Value on a Recurring Basis

Assets measured at fair value on a recurring basis at March 31, 2019 are as follows (amounts in millions):

	Quoted Prices in Active Markets for  Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Total Balance
Assets
Cash and cash equivalents:
Money market mutual funds	$	8.3	$	—	$	8.3
Deposit accounts	—		420.3		420.3
Short-term investments:
Marketable equity securities	2.3		—		2.3
Total assets measured at fair value	$	10.6	$	420.3	$	430.9

Assets measured at fair value on a recurring basis at March 31, 2018 are as follows (amounts in millions):

	Quoted Prices in Active Markets for  Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Total Balance
Assets
Cash and cash equivalents:
Money market mutual funds	$	121.0	$	—	$	121.0
Deposit accounts	—		641.6		641.6
Commercial Paper	—		118.7		118.7
Government agency bonds	—		20.0		20.0
Short-term investments:
Marketable equity securities	2.8		—		2.8
Corporate bonds and debt	—		542.9		542.9
Time deposits	—		11.5		11.5
Government agency bonds	—		723.2		723.2
Municipal bonds - taxable	—		14.9		14.9
Total assets measured at fair value	$	123.8	$	2,072.8	$	2,196.6