Investments - Additional Information (Detail) (USD $)	9 Months Ended			9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 Stannica Llc	Dec. 31, 2011 Stannica Llc	Sep. 30, 2012 Joint Venture Saudi Organometallic Chemicals Company	Sep. 30, 2011 Joint Venture Saudi Organometallic Chemicals Company
Schedule of Investments [Line Items]
Long-term advances to joint venture	$ 22,500,000
Ownership percentage, joint venture				50.00%
Interest rate margin over LIBOR				1.275%
Interest rate percentage				1.63%
Long-term advances to joint venture, maturity date				Dec. 31, 2021
Capital contributions to SOCC					10,900,000
Carrying value of unconsolidated investment		$ 5,600,000	$ 7,300,000