Business Segment and Geographic Disclosures (Detail) - Reporting Segment Net Sales and Gross Margin (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues from external customers	$ 21,482	$ 33,555	$ 60,333	$ 85,131
Cost of sales	(11,582)	(18,455)	(34,069)	(48,734)
Gross margin	9,900	15,100	26,264	36,397
Selling, general and administrative	(8,080)	(9,304)	(25,783)	(27,069)
Research and development	(379)	(461)	(848)	(1,824)
Operating income (loss)	1,441	5,335	(367)	7,504
Air Pollution Control Segment
Revenues from external customers	11,140	23,420	33,178	56,606
Cost of sales	(6,621)	(13,718)	(21,339)	(35,384)
Gross margin	4,519	9,702	11,839	21,222
Selling, general and administrative		0	0	0
Research and development		0	0	0
Operating income (loss)	4,519	9,702	11,839	21,222
FUEL CHEM Segment
Revenues from external customers	10,342	10,135	27,155	28,525
Cost of sales	(4,961)	(4,737)	(12,730)	(13,350)
Gross margin	5,381	5,398	14,425	15,175
Selling, general and administrative		0	0	0
Research and development		0	0	0
Operating income (loss)	5,381	5,398	14,425	15,175
Other
Revenues from external customers		0	0	0
Cost of sales		0	0	0
Gross margin		0	0	0
Selling, general and administrative	(8,080)	(9,304)	(25,783)	(27,069)
Research and development	(379)	(461)	(848)	(1,824)
Operating income (loss)	$ (8,459)	$ (9,765)	$ (26,631)	$ (28,893)

The aggregate cost of goods produced and sold and services rendered during the reporting period.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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The net result for the period of deducting operating expenses from operating revenues.

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No definition available.

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- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 1

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-Topic 730

-SubTopic 10

-Section 50

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.4)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 4

-Article 5

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section 30

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