Segment Reporting (Detail) - Company`s reportable segments (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Net sales	$ 60,537	$ 61,607
Income (loss) from operations	(7,837)	(6,523)
Depreciation and amortization	1,430	1,748
Capital expenditures	236	619
Total assets	35,441	41,115
Heavy Duty Diesel Systems [Member]
Net sales	40,666	47,460
Income (loss) from operations	(602)	1,449
Depreciation and amortization	1,238	1,536
Capital expenditures	135	435
Total assets	40,182	45,660
Catalyst [Member]
Net sales	24,322	20,789
Income (loss) from operations	(1,816)	(970)
Depreciation and amortization	192	212
Capital expenditures	101	184
Total assets	37,637	35,626
Corporate [Member]
Income (loss) from operations	(5,469)	(6,677)
Eliminations [Member]
Net sales	(4,451)	(6,642)
Income (loss) from operations	50	(325)
Total assets	(43,550)	(41,348)
Discontinued Operations [Member]
Total assets	$ 1,172	$ 1,177