Note 9 - Segment Information (Details) - Segment Information (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Net revenues from unaffiliated customers	$ 12,343	$ 11,218	$ 21,140	$ 20,191
Earnings (loss) before income tax expense (benefit):
Earnings (loss) before income tax expense (benefit)	2,054	1,487	2,465	1,857
Net earnings (loss):
Net earnings (loss)	1,357	1,003	1,643	1,295
Thermal Products [Member]
Segment Reporting Information [Line Items]
Net revenues from unaffiliated customers	6,116	5,772	11,359	11,670
Earnings (loss) before income tax expense (benefit):
Earnings (loss) before income tax expense (benefit)	1,207	1,078	2,018	2,236
Net earnings (loss):
Net earnings (loss)	797	727	1,361	1,641
Mechanical Products [Member]
Segment Reporting Information [Line Items]
Net revenues from unaffiliated customers	4,137	3,798	6,184	5,591
Earnings (loss) before income tax expense (benefit):
Earnings (loss) before income tax expense (benefit)	637	290	354	(396)
Net earnings (loss):
Net earnings (loss)	421	196	224	(346)
Electrical Products [Member]
Segment Reporting Information [Line Items]
Net revenues from unaffiliated customers	2,090	1,648	3,597	2,930
Earnings (loss) before income tax expense (benefit):
Earnings (loss) before income tax expense (benefit)	400	207	405	199
Net earnings (loss):
Net earnings (loss)	264	140	268	134
Corporate Segment [Member]
Earnings (loss) before income tax expense (benefit):
Earnings (loss) before income tax expense (benefit)	(190)	(88)	(312)	(182)
Net earnings (loss):
Net earnings (loss)	$ (125)	$ (59)	$ (210)	$ (133)