CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Income Statement [Abstract]
Net sales	$ 134,227		$ 97,995		$ 408,246		$ 298,075
Cost of sales	105,663		77,501		318,830		233,179
Gross profit	28,564		20,494		89,416		64,896
Selling, product development and administrative expenses	22,785		13,108		63,438		41,472
Operating income	5,779	[1]	7,386	[1]	25,978	[1]	23,424	[1]
Interest expense	327		77		819		231
Other (income) expense, net	(508)		(16)		(154)		44
Income before income taxes	5,960		7,325		25,313		23,149
Income tax expense	1,802		2,750		9,199		8,127
Net income	$ 4,158		$ 4,575		$ 16,114		$ 15,022
Earnings per share:
Basic (usd per share)	$ 0.25		$ 0.28		$ 0.97		$ 0.90
Diluted (usd per share)	$ 0.24		$ 0.27		$ 0.95		$ 0.89
Weighted average number of common shares outstanding:
Basic (in shares)	16,684		16,437		16,615		16,599
Diluted (in shares)	17,043		16,735		16,967		16,888

[1] Industrial Filtration segment reports results for the period following the date of acquisition of February 20, 2014 through September 30, 2014.