Concentrations - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Sales Revenue
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer	50.01%	47.81%	50.85%	45.96%
Sales Revenue | Customer One
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer	29.45%		34.43%
Sales Revenue | Customer Two
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer	20.56%		16.42%
Accounts Receivable
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer			31.50%	10.00%
Accounts Receivable | Customer One
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer				21.95%
Accounts Receivable | Customer Two
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer				12.75%