Segments - Reconciliation of Revenue from Segments to Consolidated (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Sales to external customers	$ 1,305,493	$ 1,308,959	$ 4,005,560	$ 4,062,303
Equity in earnings (losses) of unconsolidated affiliates	9,267	15,215	29,595	26,943
EBITDA	75,445	104,829	278,090	251,453
Investment in unconsolidated affiliates	164,504	158,692	164,504	158,692	155,887
Depreciation and amortization	27,857	23,237	78,798	71,037
Operating Segments [Member] | Emulsion Polymers, Latex [Member]
Segment Reporting Information [Line Items]
Sales to external customers	328,394	332,102	975,382	1,033,820
EBITDA	25,389	24,052	75,717	72,825
Depreciation and amortization	6,456	6,068	20,095	19,539
Operating Segments [Member] | Emulsion Polymers, Synthetic Rubber [Member]
Segment Reporting Information [Line Items]
Sales to external customers	155,452	141,549	497,091	474,139
EBITDA	26,590	12,805	106,722	71,410
Depreciation and amortization	8,653	7,051	24,298	21,490
Operating Segments [Member] | Plastics, Styrenics [Member]
Segment Reporting Information [Line Items]
Sales to external customers	560,527	576,276	1,744,608	1,775,573
Equity in earnings (losses) of unconsolidated affiliates	10,854	15,208	33,196	27,586
EBITDA	21,628	66,005	91,060	108,968
Investment in unconsolidated affiliates	131,460	121,403	131,460	121,403
Depreciation and amortization	7,279	6,861	22,028	21,765
Operating Segments [Member] | Plastics, Engineered Polymers [Member]
Segment Reporting Information [Line Items]
Sales to external customers	261,120	259,032	788,479	778,771
Equity in earnings (losses) of unconsolidated affiliates	(1,587)	7	(3,601)	(643)
EBITDA	1,838	1,967	4,591	(1,750)
Investment in unconsolidated affiliates	33,044	37,289	33,044	37,289
Depreciation and amortization	3,856	1,932	8,796	5,405
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 1,613	$ 1,325	$ 3,581	$ 2,838