Investments - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jun. 30, 2012 Stannica Llc	Dec. 31, 2011 Stannica Llc	Jun. 30, 2012 Joint Venture Saudi Organometallic Chemicals Company	Jun. 30, 2011 Joint Venture Saudi Organometallic Chemicals Company
Schedule of Investments [Line Items]
Long-term advances to joint venture	$ 10,000,000	$ 10,000,000
Ownership percentage, joint venture					50.00%
Commitment to fund joint venture, maximum					22,500,000
Interest rate margin over LIBOR					1.275%
Interest rate percentage					1.74%
Long-term advances to joint venture, maturity date					Dec. 31, 2021
Loan receivable outstanding					10,000,000
Capital contributions to SOCC						10,900,000
Carrying value of unconsolidated investment			$ 6,500,000	$ 7,300,000