Significant Customers - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Customer	Jun. 30, 2012 Customer	Jun. 30, 2013 Customer	Jun. 30, 2012 Customer	Dec. 31, 2012
Revenue, Major Customer [Line Items]
Number of significant customer	2	3	2	1
Trade receivables	10.00%		10.00%
Accounts receivable	64.00%		64.00%		93.00%
Customer One [Member]
Revenue, Major Customer [Line Items]
Revenue	30.00%	44.00%	46.00%	44.00%
Customer Two [Member]
Revenue, Major Customer [Line Items]
Revenue	27.00%	14.00%	15.00%
Customer Three [Member]
Revenue, Major Customer [Line Items]
Revenue		14.00%
Number of other customers accounted for more than 10% of revenue	0		0
Minimum [Member] | Customer One [Member]
Revenue, Major Customer [Line Items]
Revenue			10.00%