Segment Information - PP&E and Total Assets by Business Segment (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	$ 35,664	$ 28,310	$ 20,681
Additions to PP&E:
Total additions to PP&E	240,104	166,419	150,805
Total assets at December 31:
Total assets	1,137,005	1,083,097	576,612
Operating Segments [Member] | Chemical [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	30,364	23,497	16,355
Additions to PP&E:
Total additions to PP&E	238,070	160,343	141,399
Total assets at December 31:
Total assets	929,745	842,725	394,479
Operating Segments [Member] | Climate Control [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	4,946	4,707	4,250
Additions to PP&E:
Total additions to PP&E	1,859	5,576	5,816
Total assets at December 31:
Total assets	133,183	159,960	139,526
Operating Segments [Member] | Other [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	34	49	32
Additions to PP&E:
Total additions to PP&E	27	65	889
Total assets at December 31:
Total assets	5,960	6,832	8,204
Corporate [Member] | Corporate Assets [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	320	57	44
Additions to PP&E:
Total additions to PP&E	148	435	2,701
Total assets at December 31:
Total assets	$ 68,117	$ 73,580	$ 34,403