Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Net sales	$ 180,923	$ 182,313	$ 535,358	$ 509,970
Operating income for reportable segments	29,866	32,927	96,997	90,459
Reconciliation from Segment Totals to Consolidated [Abstract]
Non-operating expenses	(13,185)	(14,800)	(45,166)	(42,318)
Amortization	(818)	(623)	(2,283)	(1,596)
Operating income	15,863	17,504	49,548	46,545
Interest expense	(1,034)	(1,166)	(3,359)	(3,584)
Interest income	149	262	409	805
Other income, net	322	2,740	529	4,070
Income before taxes and equity in net income of associated companies	15,300	19,340	47,127	47,836
Metalworking Process Chemicals [Member]
Segment Reporting Information [Line Items]
Net sales	168,732	171,222	499,718	478,727
Operating income for reportable segments	26,772	30,443	88,396	83,527
Coatings [Member]
Segment Reporting Information [Line Items]
Net sales	11,222	10,378	32,695	29,347
Operating income for reportable segments	3,016	2,452	8,328	6,861
All Other Segments [Member]
Segment Reporting Information [Line Items]
Net sales	969	713	2,945	1,896
Operating income for reportable segments	$ 78	$ 32	$ 273	$ 71