Secured Debt Included in Consolidated Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Less current portion of debt	$ (253)	$ (788)
Long-term portion of debt	561	9,339
TriplePoint Capital LLC
Debt Instrument [Line Items]
Secured debt	897	11,069
Less: Unamortized debt discounts	(58)	(942)
Secured debt, net	839	10,127
Less current portion of debt	(253)	(788)
Long-term portion of debt	586	9,339
TriplePoint Capital LLC | TriplePoint - September 2010 Advance
Debt Instrument [Line Items]
Secured debt		917
TriplePoint Capital LLC | TriplePoint - October 2011 Advance
Debt Instrument [Line Items]
Secured debt		6,657
TriplePoint Capital LLC | TriplePoint - January 2012 Advance
Debt Instrument [Line Items]
Secured debt		3,495
TriplePoint Capital LLC | TriplePoint - May 2014 Advance
Debt Instrument [Line Items]
Secured debt	$ 897