STOCK-BASED COMPENSATION (Tables)

3 Months Ended

Jun. 30, 2015

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   June 30,
(in thousands)	2015			2014
Cost of revenues	$	779		$	535
Research, development and engineering	2,359			1,751
Selling, general and administrative	4,912			4,019
Stock-based compensation included in operating expenses	7,271			5,770
Total stock-based compensation	8,050			6,305
Income tax benefit	(2,322		)	(1,789		)
Total stock-based compensation, net of tax	$	5,728		$	4,516

Summary of Stock Option Activity

The following is a summary of the Company’s stock option activity during the three months ended June 30, 2015:

	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, 2015	1,558		$	36.59
Options granted	141		$	53.91
Options exercised	(100	)	$	30.55
Options forfeited or expired	(26	)	$	46.67
Outstanding at June 30, 2015	1,573		$	38.37	4.1	$	29,532
Vested or expected to vest at June 30, 2015	1,533		$	38.06	4.0	$	29,248
Exercisable at June 30, 2015	1,083		$	33.86	3.2	$	25,215

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 three months ended June 30, 2015:

	Number of Shares		Weighted Average Grant Date Fair Value
	(in thousands)
Non-vested at March 31, 2015	1,290		$	42.67
Restricted stock granted	613		$	54.97
Restricted stock vested	(466	)	$	41.82
Restricted stock forfeited	(27	)	$	44.84
Non-vested at June 30, 2015	1,410		$	48.26

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   June 30,
Employee Stock Options	2015			2014
Expected volatility	27.3		%	28.4		%
Risk-free interest rate	1.2		%	1.4		%
Expected dividend yield	1.1		%	1.4		%
Expected life (in years)	4.2			4.2
Weighted-average grant date fair value	$	11.48		$	9.21