Stock-Based Compensation (Tables)

9 Months Ended

Dec. 31, 2018

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 consolidated statements of operations for the three and nine months ended December 31, 2018 and 2017:

	For the Three Months Ended December 31,				For the Nine Months Ended December 31,
		2018		2017		2018		2017
	(in $000's)
Cost of product revenue	$	773	$	489	$	2,122	$	1,221
Research and development		2,638		1,673		7,222		4,217
Selling, general and administrative		12,167		9,070		34,413		23,732
	$	15,578	$	11,232	$	43,757	$	29,170

Summary of Stock Option Activity

The following table summarizes the stock option activity for the nine months ended December 31, 2018:

						Weighted
				Weighted		Average		Aggregate
				Average		Remaining		Intrinsic
	Options			Exercise		Contractual		Value
	(in thousands)			Price		Term (years)		(in thousands)
Outstanding at beginning of period		1,282		$	46.18		5.31
Granted		78			381.62
Exercised		(435	)		25.36
Cancelled and expired		(19	)		145.89
Outstanding at end of period		906		$	83.90		5.74	$	222,852
Exercisable at end of period		668		$	39.86		4.78	$	190,646
Options vested and expected to vest at end of period		896		$	83.73		5.72	$	220,460

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

The weighted average grant-date fair values and weighted average assumptions used in the calculation of fair value of stock options granted during the three and nine months ended December 31, 2018 and 2017 was as follows:

	For the Three Months Ended December 31,						For the Nine Months Ended December 31,
		2018			2017			2018			2017
Weighted average grant-date fair value	$	117.50		$	70.14		$	142.08		$	51.20
Valuation assumptions:
Risk-free interest rate		2.81	%		2.13	%		2.93	%		1.86	%
Expected option life (years)		4.04			4.08			4.04			4.07
Expected volatility		45.2	%		42.2	%		42.8	%		43.6	%

Summary of Restricted Stock Units Activity

The following table summarizes activity of restricted stock units for the nine months ended December 31, 2018:

	Number of Shares			Weighted Average Grant Date Fair Value
	(in thousands)			(per share)
Restricted stock units at beginning of period		880		$	109.01
Granted		193		$	379.30
Vested		(418	)	$	103.66
Forfeited		(25	)	$	187.05
Restricted stock units at end of period		630		$	192.16