Discontinued Operations - Schedule of Income from Discontinued Operations (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other income (expense):
(Loss) income from discontinued operations before income taxes	$ (1,150,000)	$ 603,000	$ (1,652,000)	$ 578,000
(Loss) income from discontinued operations, net of tax	(700,000)	400,000	(1,005,000)	402,000
Discontinued Operations, Disposed of by Sale [Member] | RFL [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales		5,449,000		14,368,000
Costs and expenses:
Cost of products sold		2,624,000		7,117,000
Engineering and product development		502,000		1,363,000
Selling, general and administrative		1,415,000		4,319,000
Depreciation and amortization		98,000		319,000
Total cost and expenses		4,639,000		13,118,000
Income from operations		810,000		1,250,000
Other income (expense):
Interest expense		(2,000)		(31,000)
(Loss) income from discontinued operations before income taxes		808,000		1,219,000
Income tax provision		283,000		427,000
(Loss) income from discontinued operations, net of tax		525,000		792,000
Discontinued Operations Not Yet Disposed [Member] | Environmental costs [Member]
Other income (expense):
(Loss) income from discontinued operations before income taxes	(1,150,000)	(205,000)	(1,652,000)	(641,000)
(Loss) income from discontinued operations, net of tax	$ (700,000)	$ (125,000)	$ (1,005,000)	$ (390,000)