Shareholders' Equity (Tables)

6 Months Ended

Jun. 30, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Fair Values of Stock Option Grants Estimated with Weighted Average Assumptions

The fair values of our stock option grants were estimated with the following weighted average assumptions:

	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Dividend yield		0	%		0	%		0	%		0	%
Expected life	5.2 years			3.3 years			5.3 years			3.3 years
Expected volatility		55	%		52	%		54	%		53	%
Risk-free interest rate		2.7	%		1.6	%		2.5	%		1.7	%

Stock-Based Compensation Expense

The impact on our results of operations from stock-based compensation expense was as follows (in thousands, except per share amounts):  

	Three Months Ended June 30,					Six Months Ended June 30,
	2018			2017		2018		2017
Cost of revenue — professional engineering service	$	8		$	20	$	19	$	85
Selling, general and administrative		(80	)		320		184		604
Research and development		56			71		112		121
Total stock-based compensation expense	$	(16	)	$	411	$	315	$	810
Per diluted share	$	(0.00	)	$	0.03	$	0.02	$	0.06

Summary of Stock Option Activity

The following table summarizes stock option activity under the Plans:

						Weighted Average
						Remaining
				Weighted Average		Contractual Life		Aggregate
	Number of Shares			Exercise Price		(in years)		Intrinsic Value
Balance at December 31, 2017		1,912,161		$	4.88		7.61	$	781,735
Granted		256,643			3.95
Exercised		(2,422	)		3.59
Forfeited		(265,697	)		4.90
Expired		(22,605	)		5.72
Balance at June 30, 2018		1,878,080		$	4.74		6.28	$	5,080
Vested and expected to vest at June 30, 2018		1,784,268		$	4.73		6.14	$	5,080
Exercisable at June 30, 2018		1,181,163		$	4.60		4.80	$	5,080

Summary of Certain Additional Information about Stock Options

The following table summarizes certain information about stock options:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Weighted average grant-date fair value of options granted during the period	$	1.77	$	2.64	$	1.98	$	2.80
Options in-the-money (in shares)		19,550		1,755,762		19,550		1,755,762
Aggregate intrinsic value of options exercised during the period	$	1,578	$	17,412	$	1,853	$	57,833

Summary of Restricted Stock Unit Activity

The following table summarizes RSU activity under the Plans:

	Number of			Weighted Average
	Shares			Award Price
Unvested at December 31, 2017		116,968		$	5.33
Granted		136,505			3.21
Vested		(46,764	)		5.14
Forfeited		(26,312	)		5.31
Unvested at June 30, 2018		180,397		$	3.78
Expected to vest after June 30, 2018		165,730		$	3.75

Summary of Shares of Common Stock Reserved for Future Issuance under Plans

The following table summarizes our shares of common stock reserved for future issuance under the Plans as of June 30, 2018:

	June 30, 2018
Stock options outstanding		1,878,080
Restricted stock units outstanding		180,397
Stock options available for future grant		1,110,722
Common stock reserved for future issuance		3,169,199