Debt (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Total debt, Principal	$ 2,157	$ 7,773
Total debt, Unamortized amount	0	(49)
Total debt	2,157	7,724
Less: debt - current, Principal	(2,157)	(4,857)
Less: debt - current, Unamortized Discount	0	29
Less: debt - current	(2,157)	(4,828)
Debt - non-current, Principal	0	2,916
Debt - non-current, Unamortized Discount	0	(20)
Debt - non-current	0	2,896
Comerica - Growth Capital Loan A, due 2015
Debt Instrument [Line Items]
Total debt, Principal		4,583
Total debt, Unamortized amount		(49)
Total debt		4,534
Comerica - Revolving Line of Credit, due 2014
Debt Instrument [Line Items]
Total debt, Principal	2,157	3,190
Total debt, Unamortized amount	0	0
Total debt	$ 2,157	$ 3,190