Marketable Securities and Fair Value Measurements (Tables)

12 Months Ended

Mar. 31, 2017

Fair Value Disclosures [Abstract]

Marketable Securities by Balance Sheet Classification

The Company’s marketable securities at March 31, 2017 and 2016 are classified on the balance sheet as follows:

	March 31, 2017		March 31, 2016
	(in $000's)
Short-term marketable securities (within one year to maturity)	$	190,908	$	163,822
Long-term marketable securities (one to two years to maturity)		47,143		1,000
	$	238,051	$	164,822

Marketable Securities

The Company’s marketable securities at March 31, 2017 and 2016 are invested in the following:

	Amortized		Gross Unrealized		Gross Unrealized			Fair Market
	Cost		Gains		Losses			Value
	(in $000's)
March 31, 2017:
Short-term U.S. Treasury mutual fund securities	$	45,199	$	—	$	(13	)	$	45,186
Short-term government-backed securities		90,199		1		(87	)		90,113
Short-term corporate debt securities		55,465		—		(31	)		55,434
Long-term U.S. Treasury mutual fund securities		1,998		—		(3	)		1,995
Long-term government-backed securities		43,484		5		(18	)		43,471
Long-term corporate debt securities		1,853		—		(1	)		1,852
	$	238,198	$	6	$	(153	)	$	238,051

	Amortized		Gross Unrealized		Gross Unrealized			Fair Market
	Cost		Gains		Losses			Value
	(in $000's)
March 31, 2016:
U.S. Treasury mutual fund securities	$	45,635	$	21	$	—		$	45,656
Short-term government-backed securities		118,125		45		(4	)		118,166
Long-term government-backed securities		999		1		—			1,000
	$	164,759	$	67	$	(4	)	$	164,822

Financial Instruments Measured at Fair Value

The following table presents the Company’s fair value hierarchy for its financial instruments measured at fair value as of March 31, 2017 and 2016:

	Level 1		Level 2		Level 3		Total
March 31, 2017:	(in $000's)
Assets
Short-term U.S. Treasury mutual fund securities	$	—	$	45,186	$	—	$	45,186
Short-term government-backed securities		—		90,113		—		90,113
Short-term corporate debt securities		—		55,434		—		55,434
Long-term U.S. Treasury mutual fund securities		—		1,995		—		1,995
Long-term government-backed securities		—		43,471		—		43,471
Long-term corporate debt securities		—		1,852		—		1,852
Liabilities
Contingent consideration		—		—		9,153		9,153

	Level 1		Level 2		Level 3		Total
March 31, 2016:	(in $000's)
Assets
U.S. Treasury mutual fund securities	$	—	$	45,656	$	—	$	45,656
Short-term government-backed securities		—		118,166		—		118,166
Long-term government-backed securities		—		1,000		—		1,000
Liabilities
Contingent consideration		—		—		7,563		7,563

Valuation Method Used to Calculate Level 3 Liabilities Measured at Estimated Fair Value of Contingent Consideration Related to Acquisition

This liability is reported as Level 3 as the estimated fair value of the contingent consideration related to the acquisition of the ECP requires significant management judgment or estimation and is calculated using the following valuation methods:

	Fair Value at				Weighted Average
	March 31, 2017			Significant	(range, if
	(in $000's)		Valuation Methodology	Unobservable Input	applicable)
Clinical and regulatory milestone	$	5,395	Probability weighted income approach	Projected fiscal year of milestone payments	2019 to 2022
				Discount rate	2.6% to 3.3%
				Probability of occurrence	Probability adjusted level of 40% for the base case scenario and 5% to 20% for various upside and downside scenarios
Revenue-based milestone		3,758	Monte Carlo simulation model	Projected fiscal year of milestone payments	2023 to 2035
				Discount rate		18%
				Expected volatility for forecasted revenues		50%
	$	9,153

Change in Fair Value of Contingent Consideration as Determined by Level 3 Inputs

The following table summarizes the change in fair value, as determined by Level 3 inputs, of the contingent consideration for the fiscal years ended March 31, 2017, 2016 and 2015:  

	Fiscal Years Ended March 31,
		2017		2016		2015
	(in $000's)
Level 3 liabilities, beginning balance	$	7,563	$	6,510	$	—
Additions		—		—		6,000
Payments		—		—		—
Change in fair value		1,590		1,053		510
Level 3 liabilities, ending balance	$	9,153	$	7,563	$	6,510