Concentrations - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Sales Revenue
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer	53.39%	42.92%	51.32%	44.89%
Sales Revenue | Customer One
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer	31.79%		37.42%
Sales Revenue | Customer Two
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer	21.60%		13.90%
Accounts Receivable | Customer One
Concentration Risk [Line Items]
Percentage of revenues derived and gross trade accounts receivable customer			28.73%	20.25%