Investments (Tables)

3 Months Ended

Jun. 30, 2018

Investments [Abstract]

Summary of available-for-sale securities

The following is a summary of available-for-sale debt securities at June 30, 2018 (in millions):

	Available-for-sale Debt Securities
	Adjusted Cost		Gross Unrealized Gains	Gross Unrealized Losses	Estimated Fair Value
Time deposits	$	11.3	—	—	$	11.3

At June 30, 2018, short-term investments of $14.5 million included available-for-sale debt securities of $11.3 million and marketable equity securities of $3.2 million.

The following is a summary of available-for-sale debt securities at March 31, 2018 (in millions):

	Available-for-sale Debt Securities
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale debt securities:
Government agency bonds	$	723.2	$	—	$	—	$	723.2
Municipal bonds - taxable	14.9		—		—		14.9
Time deposits	11.5		—		—		11.5
Corporate bonds and debt	542.9		—		—		542.9
Total	$	1,292.5	$	—	$	—	$	1,292.5

Summary of investments classified by contractual maturity date

The amortized cost and estimated fair value of the available-for-sale debt securities at June 30, 2018, by contractual maturity are shown below (in millions). Expected maturities can differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties, and the Company views its available-for-sale debt securities as available for current operations.

	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale debt securities
Due in one year or less	$	11.3	$	—	$	—	$	11.3