Debt - Additional Information (Detail)	3 Months Ended		9 Months Ended			9 Months Ended				9 Months Ended				9 Months Ended		9 Months Ended
	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Dec. 31, 2012 USD ($)	Sep. 30, 2013 Chinese Credit Facility-BOA [Member] USD ($)	Sep. 30, 2013 Chinese Credit Facility-BOA [Member] CNY	Sep. 30, 2012 Chinese Credit Facility-BOA [Member] USD ($)	Sep. 30, 2012 Chinese Credit Facility-BOA [Member] CNY	Sep. 30, 2013 Chinese Credit Facility-JPM [Member] USD ($)	Sep. 30, 2013 Chinese Credit Facility-JPM [Member] CNY	Apr. 30, 2012 Chinese Credit Facility-JPM [Member] USD ($)	Apr. 30, 2012 Chinese Credit Facility-JPM [Member] CNY	Sep. 30, 2013 Term Loan [Member]	Dec. 20, 2011 Term Loan [Member] USD ($)	Sep. 30, 2013 Revolving Credit Facility [Member] USD ($)	Dec. 20, 2011 Revolving Credit Facility [Member] USD ($)	Sep. 30, 2013 Letters of Credit [Member] USD ($)	Sep. 30, 2013 Borrowings on Same Day-notice [Member] USD ($)	Sep. 30, 2013 Chinese Credit Facility [Member] USD ($)	Dec. 31, 2012 Chinese Credit Facility [Member] USD ($)
Debt Instrument [Line Items]
Maximum borrowing limits								$ 30,000,000	189,000,000						$ 600,000,000
Term Loan Facility, principal amount	350,000,000		350,000,000												400,000,000
Period of Term Loan Facility															5 years		5 years
Borrowings, maturity date														Dec. 01, 2016		Dec. 01, 2016
Borrowing capacity under Revolving Credit Facility																	200,000,000	40,000,000	40,000,000
Borrowings, interest rate description			Interest at LIBOR plus 150 basis points, or the Eurocurrency Spread, or the alternate base rate ("ABR") plus 50 basis points
Borrowings alternate base rate			0.50%			100.00%	100.00%			100.00%	100.00%			1.50%
Commitment fee on undrawn amount			0.225%
Borrowings, interest rate basis						5.60%	5.60%			5.60%	5.60%			1.70%
Principal repayment of term loan			2.50%
Principal payments on long-term debt			30,000,000	15,000,000
Revolving Credit Facility borrowings	26,177,000		26,177,000		32,145,000	11,900,000				14,300,000						0
Total interest and commitments fees	1,800,000	2,100,000	5,900,000	6,500,000
Short term borrowings outstanding																				26,200,000	32,100,000
Extended revolving credit facility of Chinese subsidiaries with BOA						22,000,000	138,600,000					20,000,000	125,000,000
Revolving credit facility, maturity term						1 year	1 year			1 year	1 year
Payment of interest on Chinese Credit Facilities						$ 10,900,000	68,283,570			$ 3,900,000	24,281,546
Interest rate of Chinese Credit Facility BOA						Chinese Credit Facility-BOA currently bears interest at a rate based on 100% of the People's Bank of China's base rate and was 5.6% as of September 30, 2013.	Chinese Credit Facility-BOA currently bears interest at a rate based on 100% of the People's Bank of China's base rate and was 5.6% as of September 30, 2013.			Chinese Credit Facility-JPM currently bears interest at a rate based on 100% of the People's Bank of China's base rate and was 5.6% as of September 30, 2013.	Chinese Credit Facility-JPM currently bears interest at a rate based on 100% of the People's Bank of China's base rate and was 5.6% as of September 30, 2013.