Long-term Debt - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended			1 Months Ended
	Oct. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2014	Jul. 31, 2014 Installment	Aug. 31, 2013 Installment
Line of Credit Facility [Line Items]
Loss on extinguishment of debt		$ (581,000)	$ 0	$ 0
Percentage of redemption fee		4.00%
Principal and interest payment frequency		The Company is required to pay only interest for the first five years of the term. Principal payments are due in four equal installments during the sixth year of the term.
Minimum liquidity covenant	2,000,000
Annual revenue recognized	40,000,000
Increase in annual revenue in fiscal years	15,000,000
Annual revenue recognize description	The term loan agreement also includes a $2.0 million minimum liquidity covenant and revenue-based financial covenants, which shall initially be $40.0 million for 2014 with annual increases of $15.0 million for each subsequent fiscal year thereafter.
Amount financed under lease		506,000	410,000
Term Loan Facility [Member]
Line of Credit Facility [Line Items]
Credit facility, borrowing capacity					45,000,000
Credit facility, borrowing capacity					51,000,000
Credit facility, Outstanding					20,000,000
End of term payment					1,000,000
Amount of make-whole premium payment					300,000
Total incurred and recorded repayment					1,400,000
Percentage of accrue interest	12.50%
Percentage of deferred payment	3.50%	3.50%
End of deferred payment term		First four years term
Loss on extinguishment of debt					600,000
Credit facility, additional borrowing capacity	15,000,000		5,000,000	13,000,000
Term Loan Facility [Member] | October 2014 [Member]
Line of Credit Facility [Line Items]
Credit facility, additional borrowing capacity	10,000,000
Series D Preferred Stock [Member]
Line of Credit Facility [Line Items]
Number of shares issuable upon exercise of warrants				76,940
Exercise price of warrants				$ 8.45
Series E Preferred Stock [Member]
Line of Credit Facility [Line Items]
Number of shares issuable upon exercise of warrants			10,418	20,837
Exercise price of warrants				$ 14.40
Series E Preferred Stock [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Fair value of warrants, volatility rate assumed				57.00%
Fair value of warrants, risk free rate assumed				1.63%
Series E Preferred Stock [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Fair value of warrants, volatility rate assumed				61.00%
Fair value of warrants, risk free rate assumed				2.20%
Equipment [Member]
Line of Credit Facility [Line Items]
Term of lease						3 years	3 years
Lease expiration date						2017-06	2016-07
Amount financed under lease						$ 260,000	$ 410,000
Number of installments						36	36