Stockholder's Equity

(a) Stock Equity and Incentive Plan

The Company recognizes stock-based compensation in accordance with the provisions of ASC Topic 718, Compensation-Stock Compensation. Stock-based compensation expense, excluding compensation charges related to our employee stock purchase plan, or the ESPP, was $860 and $843 for the three months ended March 31, 2019 and 2018, respectively. As of March 31, 2019, there was $2,152 of total unrecognized compensation expense related to stock options, which is expected to be recognized over a weighted-average period of 2.68 years. As of March 31, 2019, there was $3,743 of total unrecognized compensation expense related to restricted stock awards, which is expected to be recognized over a weighted-average period of 1.93 years.

Stock Options

During the three months ended March 31, 2019, 7 stock options were exercised for common stock, and no shares of common stock were delivered to the Company as payment for the exercise price or related minimum tax withholding obligations for the exercise of such options. During the three months ended March 31, 2019, no stock options were granted and 2 stock options expired, were canceled or were forfeited. The Company estimates the fair value of each option grant on the date of grant using the Black-Scholes option-pricing model.

As of March 31, 2019, there were 1,267 options outstanding with a weighted average exercise price of $10.29 per share and 514 options exercisable with a weighted average exercise price of $10.37 per share.

Restricted Stock

During the three months ended March 31, 2019, 78 shares of restricted stock were granted with a weighted average grant date fair value of $10.59 per share, and no shares of restricted stock were forfeited. Additionally, during the three months ended March 31, 2019, 194 shares of restricted stock vested, none of which were surrendered to the Company to satisfy minimum tax withholding obligations for the vesting of such shares.

As of March 31, 2019, there were 409 shares of restricted stock outstanding that were subject to service-based vesting conditions.

As of March 31, 2019, the Company had no unvested outstanding options and no shares of restricted stock that were subject to performance-based or market-based vesting conditions.

(b) Employee Stock Purchase Plan

The Company's Amended and Restated 1996 Employee Stock Purchase Plan (ESPP) affords eligible employees the right to purchase common stock, via payroll deductions, through various offering periods at a purchase price equal to 85% of the fair market value of the common stock on the first or last day of the offering period, whichever is lower. During the three months ended March 31, 2019 and 2018, 23 and 0 shares were issued under the ESPP plan, respectively. The Company recorded compensation charges of $14 and $10 for the three months ended March 31, 2019 and 2018, respectively, related to the ESPP.

The following table presents stock-based compensation expense, including under the ESPP, in the Company's consolidated statements of operations for the three months ended March 31, 2019 and 2018:



	Three Months Ended March 31,
	2019		2018
Cost of product sales	$	41	$	71
Cost of service sales	—		—
Research and development	172		170
Sales, marketing and support	182		181
General and administrative	479		431
	$	874	$	853

(d) Accumulated Other Comprehensive Loss

Comprehensive income (loss) includes net income (loss), unrealized gains and losses from foreign currency translation, unrealized gains and losses from available for sale marketable securities and changes in fair value related to interest rate swap derivative instruments, net of tax attributes. The components of the Company’s comprehensive income (loss) and the effect on earnings for the periods presented are detailed in the accompanying consolidated statements of comprehensive income (loss).



	Foreign Currency Translation			Unrealized (Loss) Gain on Available for Sale Marketable Securities		Interest Rate Swaps			Total Accumulated Other Comprehensive Loss
Balance, December 31, 2018	$	(14,720	)	$	—	$	(11	)	$	(14,731	)
Other comprehensive income before reclassifications	1,080			—		—			1,080
Amounts reclassified from AOCI to Other income, net	—			—		8			8
Net other comprehensive income, March 31, 2019	1,080			—		8			1,088
Balance, March 31, 2019	$	(13,640	)	$	—	$	(3	)	$	(13,643	)



	Foreign Currency Translation			Unrealized (Loss) Gain on Available for Sale Marketable Securities			Interest Rate Swaps			Total Accumulated Other Comprehensive Loss
Balance, December 31, 2017	$	(11,247	)	$	(1	)	$	(69	)	$	(11,317	)
Other comprehensive income before reclassifications	2,444			1			7			2,452
Amounts reclassified from AOCI to Other income, net	—			—			15			15
Net other comprehensive income, March 31, 2018	2,444			1			22			2,467
Balance, March 31, 2018	$	(8,803	)	$	—		$	(47	)	$	(8,850	)

For additional information, see Note 4, "Marketable Securities," and Note 17, "Derivative Instruments and Hedging Activities."