Segment Information - PP&E and Total Assets by Business Segment (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	$ 20,681	$ 18,762	$ 17,329
Additions to PP&E:
Total additions to PP&E	150,805	47,957	36,545
Total assets at December 31:
Total assets	576,612	502,009	387,981
Chemical [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	16,355	14,659	13,154
Additions to PP&E:
Total additions to PP&E	141,399	39,835	28,850
Total assets at December 31:
Total assets	394,479	294,886	205,179
Climate Control [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	4,250	3,853	4,026
Additions to PP&E:
Total additions to PP&E	5,816	5,746	7,177
Total assets at December 31:
Total assets	139,526	160,515	150,635
Corporate assets and other [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	76	250	149
Additions to PP&E:
Total additions to PP&E	3,590	2,376	518
Total assets at December 31:
Total assets	$ 42,607	$ 46,608	$ 32,167