STOCK-BASED COMPENSATION (Tables)

9 Months Ended

Dec. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Expense Included in Statements of Operations

The following table summarizes the amount of stock-based compensation included in the condensed consolidated statements of operations:

	Three Months Ended   December 31,						Nine Months Ended December 31,
(in thousands)	2014			2013			2014			2013
Cost of revenues	$	685		$	686		$	1,888		$	1,859
Research, development and engineering	2,068			1,688			5,934			4,708
Selling, general and administrative	4,677			3,669			13,300			10,429
Stock-based compensation included in operating expenses	6,745			5,357			19,234			15,137
Total stock-based compensation	7,430			6,043			21,122			16,996
Income tax benefit	(2,188		)	(1,788		)	(6,216		)	(5,063		)
Total stock-based compensation, net of tax	$	5,242		$	4,255		$	14,906		$	11,933

Summary of Stock Option Activity

The following is a summary of the Company’s stock option activity during the nine months ended December 31, 2014:

	Options Outstanding
	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life	Aggregate Intrinsic Value
	(in thousands)				(in years)	(in thousands)
Outstanding at March 31, 2014	1,934		$	31.91
Options granted	298		$	47.11
Options exercised	(544	)	$	27.49
Options forfeited or expired	(40	)	$	39.83
Outstanding at December 31, 2014	1,648		$	35.92	4.2	$	29,375
Vested or expected to vest at December 31, 2014	1,610		$	35.68	4.1	$	29,097
Exercisable at December 31, 2014	1,117		$	31.97	3.3	$	24,315

Summary of Restricted Stock Activity

Restricted stock consists of awards of restricted stock and restricted stock units ("RSUs"). The following is a summary of the Company’s restricted stock activity during the nine months ended December 31, 2014:

	Number of Shares		Weighted Average Grant Date Fair Value
	(in thousands)
Non-vested at March 31, 2014	1,172		$	39.52
Restricted stock granted	653		$	45.16
Restricted stock vested	(441	)	$	38.63
Restricted stock forfeited	(82	)	$	40.99
Non-vested at December 31, 2014	1,302		$	42.55

Valuation Assumptions

At the date of grant, the Company estimated the fair value of each stock option grant and purchase right granted under the ESPP using the following weighted average assumptions:

	Three Months Ended   December 31,						Nine Months Ended December 31,
Employee Stock Options	2014			2013			2014			2013
Expected volatility	28.4		%	30.1		%	28.4		%	32.2		%
Risk-free interest rate	1.4		%	1.1		%	1.4		%	0.9		%
Expected dividend yield	1.2		%	0.9		%	1.3		%	0.9		%
Expected life (in years)	4.2			4.2			4.2			4.2
Weighted-average grant date fair value	$	11.53		$	10.15		$	10.33		$	11.15
ESPP (1)
Expected volatility							24.8		%	24.9		%
Risk-free interest rate							0.1		%	0.1		%
Expected dividend yield							1.3		%	0.9		%
Expected life (in years)							0.5			0.5
Weighted-average grant date fair value							$	10.13		$	9.58