Segment Information - Segment Financial Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Net sales	$ 149,035	$ 177,350	$ 202,223	$ 150,679	$ 177,137	$ 182,374	$ 209,275	$ 190,245	$ 679,287	$ 759,031	$ 805,256
Gross profit	30,566	48,909	38,659	25,422	40,370	33,187	65,735	44,444	143,556	183,736	223,018
Operating income									105,308	95,655	136,443
Interest expense, net									13,986	4,237	6,658
Losses on extinguishment of debt									1,296		136
Non-operating expense (income), net									100	281
Provisions for income taxes									35,421	33,594	46,208
Equity in earnings of affiliate-Climate Control									(436)	(681)	(543)
Income from continuing operations	37,473	10,250	7,486	(68)	11,622	6,710	26,130	14,324	55,141	58,786	83,984
Chemical [Member]
Segment Reporting Information [Line Items]
Net sales									380,669	477,813	511,854
Gross profit									46,165	97,692	130,687
Operating income									87,784	82,101	116,503
Non-operating expense (income), net									(1)	(1)	(1)
Chemical [Member] | Agricultural products [Member]
Segment Reporting Information [Line Items]
Net sales									167,614	217,329	231,599
Chemical [Member] | Industrial acids and other chemical products [Member]
Segment Reporting Information [Line Items]
Net sales									141,936	162,498	161,776
Chemical [Member] | Mining products [Member]
Segment Reporting Information [Line Items]
Net sales									63,042	96,538	118,479
Chemical [Member] | Natural gas [Member]
Segment Reporting Information [Line Items]
Net sales									8,077	1,448
Climate Control [Member]
Segment Reporting Information [Line Items]
Net sales									285,018	266,171	281,565
Gross profit									92,907	80,981	88,178
Operating income									30,386	25,834	32,759
Non-operating expense (income), net									(1)	(1)	(2)
Climate Control [Member] | Geothermal and water source heat pumps [Member]
Segment Reporting Information [Line Items]
Net sales									183,757	162,697	183,789
Climate Control [Member] | Hydronic fan coils [Member]
Segment Reporting Information [Line Items]
Net sales									64,541	55,812	54,379
Climate Control [Member] | Other HVAC products [Member]
Segment Reporting Information [Line Items]
Net sales									36,720	47,662	43,397
Other [Member]
Segment Reporting Information [Line Items]
Net sales									13,600	15,047	11,837
Gross profit									4,484	5,063	4,153
Operating income									1,699	2,091	1,584
Non-operating expense (income), net									(98)	(279)	3
General corporate expenses [Member]
Segment Reporting Information [Line Items]
Operating income									$ (14,561)	$ (14,371)	$ (14,403)