Segment Information - PP&E and Total Assets by Business Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	$ 40,496	$ 35,664	$ 28,310
Additions to PP&E:
Total additions to PP&E	470,509	240,104	166,419
Total assets at December 31:
Total assets	1,361,827	1,130,572	1,075,218
Operating Segments [Member] \| Chemical [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	35,239	30,364	23,497
Additions to PP&E:
Total additions to PP&E	469,558	238,070	160,343
Total assets at December 31:
Total assets	1,159,592	929,671	842,588
Operating Segments [Member] \| Climate Control [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	4,834	4,946	4,707
Additions to PP&E:
Total additions to PP&E	632	1,859	5,576
Total assets at December 31:
Total assets	148,997	133,183	159,960
Operating Segments [Member] \| Other [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	36	34	49
Additions to PP&E:
Total additions to PP&E	25	27	65
Total assets at December 31:
Total assets	5,502	5,960	6,832
Corporate [Member] \| Corporate [Member]
Depreciation, depletion and amortization of PP&E:
Total depreciation, depletion and amortization of PP&E	387	320	57
Additions to PP&E:
Total additions to PP&E	294	148	435
Total assets at December 31:
Total assets	$ 47,736	$ 61,758	$ 65,838