Stock-Based Compensation (Tables)

6 Months Ended

Sep. 30, 2020

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, 2020 and 2019:

	For the Three Months Ended September 30,				For the Six Months Ended September 30,
		2020		2019		2020		2019
	(in $000's)
Cost of  revenue	$	923	$	881	$	1,627	$	1,722
Research and development		1,705		1,823		3,147		3,706
Selling, general and administrative		8,937		10,619		16,089		21,017
	$	11,565	$	13,323	$	20,863	$	26,445

Summary of Stock Option Activity

The following table summarizes the stock option activity for the six months ended September 30, 2020:

						Weighted
				Weighted		Average		Aggregate
				Average		Remaining		Intrinsic
	Options			Exercise		Contractual		Value
	(in thousands)			Price		Term (years)		(in thousands)
Outstanding at beginning of period		869		$	112.03		5.30
Granted		65			221.12
Exercised		(153	)		36.41
Cancelled and expired		(8	)		227.25
Outstanding at end of period		774		$	134.90		5.77	$	117,144
Exercisable at end of period		592		$	98.68		4.84	$	110,352
Options vested and expected to vest at end of period		773		$	134.92		5.77	$	117,040

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

	For the Three Months Ended September 30,						For the Six Months Ended September 30,
		2020			2019			2020			2019
Weighted average grant-date fair value	$	100.51		$	70.40		$	76.10		$	95.62
Valuation assumptions:
Risk-free interest rate		0.30	%		1.54	%		0.31	%		2.02	%
Expected option life (years)		4.17			4.13			4.22			4.14
Expected volatility		43.5	%		44.2	%		42.82	%		42.3	%

Restricted Stock Units

Summary of Restricted Stock Units Activity

The following table summarizes activity of restricted stock units for the six months ended September 30, 2020:

	Number of Shares			Weighted Average Grant Date Fair Value
	(in thousands)			(per share)
Restricted stock units at beginning of period		320		$	263.92
Granted		194			254.55
Vested		(136	)		226.71
Forfeited		(101	)		267.28
Restricted stock units at end of period		277		$	274.31

Summary of Assumptions Used To Value Awards And Estimated Grant-Date Fair Value

The table below sets forth the assumptions used to value the awards and the estimated grant-date fair value:

Risk-free interest rate		0.2%
Expected volatility		35.5%
Dividend yield		—
Remaining performance period (years)	1.9 - 2.9
Estimated fair value per share	$347.05 - $349.28
Target performance (number of shares)		30,781