CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Income Statement [Abstract]
Net sales	$ 134,561	$ 148,793	$ 261,867	[1]	$ 274,019	[2]
Cost of sales	100,672	114,140	200,278		213,167
Gross profit	33,889	34,653	61,589		60,852
Selling, product development and administrative expenses	16,860	22,080	34,482		40,653
Operating income	17,029	12,573	27,107	[1]	20,199	[2]
Gain on sale of business			(18,647)		0
Interest expense	186	280	408		492
Other (income) expense, net	553	299	(469)		354
Income before income taxes	16,290	11,994	45,815		19,353
Income tax expense	5,473	3,754	16,061		7,397
Net income	$ 10,817	$ 8,240	$ 29,754		$ 11,956
Earnings per share:
Basic (usd per share)	$ 0.65	$ 0.50	$ 1.78		$ 0.72
Diluted (usd per share)	$ 0.64	$ 0.49	$ 1.74		$ 0.71
Weighted average number of common shares outstanding:
Basic (in shares)	16,681	16,618	16,759		16,580
Diluted (in shares)	16,948	16,980	17,055		16,925

[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 June 30, 2014.