Description of Business and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of computation of basic and diluted net income (loss) per share

The following table sets forth the computation of basic and diluted net loss per share (in thousands, except per share data):

	Years Ended December 31,
	2017			2016			2015
Numerator
Net loss	$	(43,129	)	$	(23,705	)	$	(22,333	)
Denominator
Weighted average common shares outstanding, basic and diluted	35,480			31,870			30,716
Net loss per share
Basic and diluted	$	(1.22	)	$	(0.74	)	$	(0.73	)

Schedule of anti-dilutive shares

The following table summarizes instruments that may be convertible into common shares that are not included in the denominator used in the diluted net loss per share calculation because to do so would be anti-dilutive (in thousands of shares):

	2017	2016	2015
Outstanding options to purchase common stock	361	414	931
Unvested restricted stock awards	26	88	245
Unvested restricted stock unit awards	2,650	1,748	885
Employee stock purchase plan awards	38	—	10
Bonus and director fees to be paid in stock awards	477	265	—
Convertible senior notes	7,245	—	—
	10,797	2,515	2,071

Revenues by product line and geographic area

Revenue by product line and geographic area is presented below (in thousands):

	Years ended December 31,
Revenue by product line:	2017		2016		2015
Ultracapacitors	$	87,709	$	71,491	$	114,525
High-voltage capacitors	42,659		45,177		41,718
Microelectronic products	—		4,576		11,129
Total	$	130,368	$	121,244	$	167,372
	Years ended December 31,
Revenue from external customers located in(1):	2017		2016		2015
China	$	44,945	$	48,191	$	87,856
United States	13,874		12,041		20,836
Germany	16,287		12,854		13,972
Hungary	13,454		11,473		11,630
All other countries (2)	41,808		36,685		33,078
Total	$	130,368	$	121,244	$	167,372
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⁽¹⁾    Location is determined by shipment destination.

⁽²⁾    Revenue from external customers located in countries included in “All other countries” does not individually comprise more than 10% of total revenue for any of the years presented.

Long-lived assets by geographic location

Long-lived assets by geographic location are as follows (in thousands):

	As of December 31,
	2017		2016		2015
United States	$	14,443	$	19,267	$	22,267
China	1,107		1,477		4,148
South Korea	4,398		—		—
Switzerland	8,096		5,376		6,021
Total	$	28,044	$	26,120	$	32,436