Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statements of Comprehensive Income (Loss) [Abstract]
Sales	$ 94,257	$ 184,426	$ 303,811	$ 367,750
Cost of sales	91,628	178,006	292,360	351,857
Gross profit	2,629	6,420	11,451	15,893
Selling expenses	236	388	403	641
General and administration expenses	2,621	2,657	5,591	5,267
Total operating expenses	2,857	3,045	5,994	5,908
(Loss) income from operations	(228)	3,375	5,457	9,985
Other income (expense):
Interest income	3,151	1,883	3,902	2,822
Interest expense	(7,045)	(2,930)	(10,441)	(7,309)
Foreign exchange gain (loss), net	4,652	(543)	6,205	(364)
Other (expense) income, net	(715)	147	(1,095)	(217)
Total other income (expense), net	43	(1,443)	(1,429)	(5,068)
(Loss) income before income taxes	(185)	1,932	4,028	4,917
Income tax expense	312	870	1,607	2,010
Net (loss) income attributable to Keyuan Petrochemicals Inc. stockholders	(497)	1,062	2,421	2,907
Dividends to Series B convertible preferred stockholders
Net (loss) income attributable to Keyuan Petrochemicals Inc. common stockholders	(497)	1,062	2,421	2,907
Net (loss) income attributable to Keyuan Petrochemicals Inc. stockholders	(497)	1,062	2,421	2,907
Other comprehensive income:
Foreign currency translation adjustment	1,101	131	1,632	708
Comprehensive income	$ 604	$ 1,193	$ 4,053	$ 3,615
Earnings (loss) per share: Attributable to common stock:
-Basic	$ (0.01)	$ 0.02	$ 0.04	$ 0.05
-Diluted	$ (0.01)	$ 0.02	$ 0.04	$ 0.05
Weighted average number of shares of common stock used in calculation:
-Basic	57,646,160	57,646,160	57,646,160	57,646,160
-Diluted	57,646,160	62,979,500	62,979,500	62,979,500