Related Party Transactions - Additional Information (Detail) (USD $)	3 Months Ended				3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Russian Standard Bank	Mar. 31, 2013 Interest on SSN	Mar. 31, 2013 Interest on bank loans	Mar. 31, 2013 Roust Trading Limited Credit Facility	Mar. 31, 2013 Roust Trading Limited Notes	May 07, 2012 Senior Notes Due 2013 Roust Trading Limited	Mar. 31, 2013 RTL Credit Facility	Mar. 31, 2013 RTL Credit Facility Roust Trading Limited	Mar. 01, 2013 RTL Credit Facility Roust Trading Limited
Related Party Transaction [Line Items]
Interest rate percentage on issued debt									3.00%		3.00%
Debt instrument issuance amount	$ 50,000,000		$ 0								$ 50,000,000	$ 50,000,000
Outstanding liability										20,000,000	50,800,000
Debt, accrued interest	27,900,000		7,100,000				800,000	1,100,000
Maximum borrowing capacity				15,100,000
Interest expense related party	$ 904,000	$ 0			$ 600,000	$ 300,000	$ 800,000