Goodwill and Other Intangibles (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2014 reporting_unit	Dec. 31, 2013
Number of reporting units	2
Goodwill	$ 28,519	$ 21,051
Fuel Chem Technology Segment [Member]
Goodwill	1,723	1,723
APC Technology Segment [Member]
Goodwill	26,796	19,328
Goodwill, Period Increase	$ 7,468

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant