Discontinued Operations - Summary of Loss from Discontinued Operations (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Other income (expense):
(Loss) from discontinued operations before income taxes	$ (266,000)	$ (292,000)
(Loss) from discontinued operations, net of tax	(162,000)	(181,000)
RFL [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales		3,839,000
Costs and expenses:
Cost of products sold		1,963,000
Engineering and product development		435,000
Selling, general and administrative		1,370,000
Depreciation and amortization		110,000
Total cost and expenses		3,878,000
(Loss) from operations		(39,000)
Other income (expense):
Interest expense		(27,000)
(Loss) from discontinued operations before income taxes		(66,000)
Income tax provision		(23,000)
(Loss) from discontinued operations, net of tax		(43,000)
Environmental costs [Member]
Other income (expense):
(Loss) from discontinued operations before income taxes	(266,000)	(226,000)
(Loss) from discontinued operations, net of tax	$ (162,000)	$ (138,000)