Stock-Based Compensation (Tables)

6 Months Ended

Sep. 30, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation Recognized

The following table summarizes stock-based compensation expense by financial statement line item in the Company’s condensed consolidated statements of operations for the three and six months ended September 30, 2017 and 2016:

	For the Three Months Ended September 30,				For the Six Months Ended September 30,
		2017		2016		2017		2016
	(in $000's)				(in $000's)
Cost of product revenue	$	372	$	221	$	731	$	520
Research and development		1,205		2,638		2,544		3,893
Selling, general and administrative		7,705		6,791		14,663		13,634
	$	9,282	$	9,650	$	17,938	$	18,047

Summary of Stock Option Activity

The following table summarizes the stock option activity for the six months ended September 30, 2017:

						Weighted
				Weighted		Average		Aggregate
				Average		Remaining		Intrinsic
	Options			Exercise		Contractual		Value
	(in thousands)			Price		Term (years)		(in thousands)
Outstanding at beginning of period		1,646		$	32.09		5.46
Granted		145			137.70
Exercised		(305	)		17.25
Cancelled and expired		(51	)		100.48
Outstanding at end of period		1,435		$	43.47		5.56	$	179,543
Exercisable at end of period		1,098		$	24.23		4.57	$	158,474
Options vested and expected to vest at end of period		1,405		$	42.84		5.51	$	176,658

Summary of Weighted Average Grant-Date Fair Values And Weighted Average Assumptions Used to Calculate Fair Value of Options Granted

The weighted average grant-date fair values and weighted average assumptions used in the calculation of fair value of options granted during the three and six months ended September 30, 2017 and 2016 was as follows:

	For the Three Months Ended September 30,						For the Six Months Ended September 30,
		2017			2016			2017			2016
Weighted average grant-date fair value	$	57.38		$	46.50		$	50.26		$	41.60
Valuation assumptions:
Risk-free interest rate		1.88	%		1.11	%		1.85	%		1.32	%
Expected option life (years)		4.06			4.14			4.07			4.13
Expected volatility		43.4	%		49.0	%		43.6	%		49.6	%

Summary of Restricted Stock Units Activity

The following table summarizes activity of restricted stock units for the six months ended September 30, 2017:

	Number of Shares			Weighted Average Grant Date Fair Value
	(in thousands)			(per share)
Restricted stock units at beginning of period		1,056		$	80.50
Granted		291		$	136.17
Vested		(355	)	$	52.84
Forfeited		(90	)	$	97.51
Restricted stock units at end of period		902		$	107.71