STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Sep. 30, 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   September 30,						Six Months Ended September 30,
(in thousands)	2014			2013			2014			2013
Cost of revenues	$	668		$	638		$	1,203		$	1,173
Research, development and engineering	2,115			1,652			3,866			3,020
Selling, general and administrative	4,604			3,675			8,623			6,760
Stock-based compensation included in operating expenses	6,719			5,327			12,489			9,780
Total stock-based compensation	7,387			5,965			13,692			10,953
Income tax benefit	(2,239		)	(1,838		)	(4,028		)	(3,275		)
Total stock-based compensation, net of tax	$	5,148		$	4,127		$	9,664		$	7,678

Summary of Stock Option Activity

The following is a summary of the Company’s stock option activity during the six months ended September 30, 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	154		$	42.66
Options exercised	(311	)	$	27.53
Options forfeited or expired	(40	)	$	39.83
Outstanding at September 30, 2014	1,737		$	33.46	3.9	$	26,225
Vested or expected to vest at September 30, 2014	1,707		$	33.31	3.9	$	26,038
Exercisable at September 30, 2014	1,256		$	30.58	3.2	$	22,573

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 six months ended September 30, 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	634		$	45.05
Restricted stock vested	(387	)	$	38.82
Restricted stock forfeited	(67	)	$	40.51
Non-vested at September 30, 2014	1,352		$	42.26

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   September 30,						Six Months Ended September 30,
Employee Stock Options	2014 (1)			2013			2014			2013
Expected volatility	n/a			30.7		%	28.4		%	33.5		%
Risk-free interest rate	n/a			1.2		%	1.4		%	0.7		%
Expected dividend yield	n/a			0.8		%	1.4		%	0.9		%
Expected life (in years)	n/a			4.2			4.2			4.2
Weighted-average grant date fair value	n/a			$	11.64		$	9.21		$	11.83
ESPP
Expected volatility	24.8		%	24.9		%	24.8		%	24.9		%
Risk-free interest rate	0.1		%	0.1		%	0.1		%	0.1		%
Expected dividend yield	1.3		%	0.9		%	1.3		%	0.9		%
Expected life (in years)	0.5			0.5			0.5			0.5
Weighted-average grant date fair value	$	10.13		$	9.58		$	10.13		$	9.58