Employee Benefits and Share-Based Compensation - (Tables)

6 Months Ended

Jun. 30, 2019

Share-based Payment Arrangement [Abstract]

Share-Based Compensation Expense Recognized in Consolidated Statements of Income

The following table sets forth the total share-based compensation expense recognized in the Company’s Condensed Consolidated Statements of Operations for the three and six months ended June 30, 2019 and 2018:

	Three months ended June 30,				Six months ended June 30,
	2019		2018		2019		2018
	(In thousands)
Cost of product and service revenues	$	1,416	$	1,177	$	2,878	$	2,196
Research and development	1,584		1,437		3,286		2,671
Selling, general, and administrative	5,260		4,624		10,506		8,899
Total share-based compensation expense	$	8,260	$	7,238	$	16,670	$	13,766

Stock Option Plans, Valuation Assumptions

The following assumptions were used to value stock options and Employee Stock Purchase Plan (“ESPP”) shares granted pursuant to the Company’s equity incentive plans for the three and six months ended June 30, 2019 and 2018:

	Three months ended June 30,				Six months ended June 30,
	2019		2018		2019		2018
Stock options
Expected life, years	4.3		4.8		4.4		4.8
Expected volatility, %	33.2	%	30.6	%	33.2	%	31.4	%
Risk-free interest rate, %	2.1	%	2.8	%	2.3	%	2.7	%
Estimated forfeiture rate, %	7.2	%	6.9	%	7.2	%	6.9	%
Dividend yield, %	—	%	—	%	—	%	—	%

Employee Stock Purchase Plan, Valuation Assumptions

	Three months ended June 30,				Six months ended June 30,
	2019		2018		2019		2018
Employee stock purchase plan shares
Expected life, years	0.5 - 2.0		0.5 - 2.0		0.5 - 2.0		0.5 - 2.0
Expected volatility, %	28.2% - 38.4%		27.7% - 33.8%		28.2% - 38.4%		27.7% - 33.8%
Risk-free interest rate, %	1.3% - 2.7%		0.7% - 2.3%		1.3% - 2.7%		0.7% - 2.3%
Dividend yield, %	—	%	—	%	—	%	—	%

Stock Option Activity under the Equity Incentive Plans

The following table summarizes the share option activity under the Company’s equity incentive plans during the six months ended June 30, 2019:

	Number of Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Years	Aggregate Intrinsic Value
	(In thousands, except per share data)
Outstanding at December 31, 2018	3,748		$	41.27	7.6	$	78,365
Granted	479		77.79
Exercised	(525	)	32.19
Expired	(4	)	40.26
Forfeited	(178	)	44.86
Outstanding at June 30, 2019	3,520		$	47.41	7.7	$	135,949
Exercisable at June 30, 2019	1,337		$	32.48	6.3	$	71,596
Vested and expected to vest at June 30, 2019 and thereafter	3,520		$	47.41	7.7	$	135,949

Restricted Stock Units Activity under the Equity Incentive Plans

Summaries of the restricted stock activity under the Company’s 2009 Equity Incentive Plan, as amended (the “2009 Plan”) are presented below for the six months ended June 30, 2019:

	Number of Shares		Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Years	Aggregate Intrinsic Value
	(In thousands, except per share data)
Restricted stock units
Outstanding at December 31, 2018	538		$	51.52	1.6	$	32,935
Granted (Awarded)	64		78.95
Vested (Released)	(87	)	40.43
Forfeited	(36	)	44.49
Outstanding and unvested at June 30, 2019	479		$	57.79	1.4	$	41,201

Restricted Stock Awards Activity under the Equity Incentive Plans

	Number of Shares		Weighted-Average Grant Date Fair Value
	(In thousands, except per share data)
Restricted stock awards
Outstanding at December 31, 2018	21		$	46.60
Granted (Awarded)	17		81.86
Vested (Released)	(21	)	46.96
Forfeited	—		—
Outstanding and unvested at June 30, 2019	17		$	81.92

Performance-Based Restricted Stock under the Equity Incentive Plans

A summary of the performance-based restricted stock activity under the 2009 Plan is presented below for the six months ended June 30, 2019:

	Number of Shares		Weighted-Average Grant Date Fair Value Per Unit
	(In thousands, except per share data)
Outstanding at December 31, 2018	197		$	34.83
Granted	71		73.38
Vested	(58	)	34.38
Forfeited	(33	)	33.84
Outstanding and unvested at June 30, 2019	177		$	50.67

Shares Reserved for Future Issuance under the Equity Incentive Plans

The Company had the following ordinary shares reserved for future issuance under its equity incentive plans as of June 30, 2019:

	Number of Shares
	(In thousands)
Share options outstanding	3,520
Non-vested restricted share awards	673
Shares authorized for future issuance	3,820
ESPP shares available for future issuance	1,703
Total shares reserved for future issuance	9,716