CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Income Statement [Abstract]
Net sales	$ 127,306	[1]	$ 125,226	[2]
Cost of sales	99,606		99,027
Gross profit	27,700		26,199
Selling, product development and administrative expenses	17,622		18,573
Operating income	10,078	[1]	7,626	[2]
Gain on sale of business	(18,647)		0
Interest expense	222		212
Other (income) expense, net	(1,022)		55
Income before income taxes	29,525		7,359
Income tax expense	10,588		3,643
Net income	$ 18,937		$ 3,716
Earnings per share:
Basic (usd per share)	$ 1.12		$ 0.22
Diluted (usd per share)	$ 1.11		$ 0.22
Weighted average number of common shares outstanding:
Basic (in shares)	16,837		16,542
Diluted (in shares)	17,109		16,852

[1] Other Products and Services reports results for the period preceding the date of disposition of January 30, 2015.

[2] Industrial Filtration segment reports results for the period following the date of acquisition of February 20, 2014 through March 31, 2014.