Debt (Details) (USD $)	12 Months Ended	0 Months Ended	1 Months Ended	4 Months Ended	12 Months Ended		0 Months Ended	1 Months Ended
	Dec. 31, 2013	Feb. 28, 2013	Feb. 28, 2013	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2012	Jul. 02, 2013	Jun. 30, 2014	Apr. 19, 2013	Dec. 31, 2011	Jan. 31, 2012	Nov. 30, 2012	Sep. 30, 2012	May 29, 2013	Apr. 28, 2008
Debt
Deferred financing costs					$ 100,000
Series A preferred stock
Estimated future principal payments due under the Credit Facility
Conversion of convertible promissory notes into Series A preferred stock (in shares)	16,623,092
Preferred stock, shares issued				23,975,000		23,975,000				23,975,000
Share price of preferred stock (in dollars per share)									$ 1.00
Number of shares of preferred stock converted into shares of common stock	(57,598,092)
Series A-1 preferred stock
Estimated future principal payments due under the Credit Facility
Conversion of convertible promissory notes into Series A preferred stock (in shares)	6,750,000
Number of shares of preferred stock converted into shares of common stock	(6,750,000)
Warrant
Debt
Exercise price (in dollars per share)					$ 7.23
Series A preferred stock warrant
Debt
Warrants exercisable into stock (in shares)							1,940,000
Exercise price (in dollars per share)							1.00
10% Convertible promissory notes | Series A preferred stock
Estimated future principal payments due under the Credit Facility
Aggregate principal amount		15,700,000	15,700,000
Accrued interest		900,000	900,000
Conversion of convertible promissory notes into Series A preferred stock (in shares)		16,623,092	16,623,092
Conversion price (in dollars per share)		$ 1.00	$ 1.00
Short term convertible notes issued January 2012
Debt
Interest rate (as a percent)											10.00%
Estimated future principal payments due under the Credit Facility
Aggregate principal amount											6,000,000
Short term convertible notes issued September and November 2012
Debt
Interest rate (as a percent)												10.00%
Estimated future principal payments due under the Credit Facility
Aggregate principal amount												9,700,000
Short term borrowings with related parties, net of debt discount												9,400,000
Short term convertible notes issued September and November 2012 | Series A preferred stock warrant | Series A preferred stock
Estimated future principal payments due under the Credit Facility
Aggregate purchase price of warrants				9,700
Short term convertible notes issued September and November 2012 | Series A preferred stock warrant | Total
Estimated future principal payments due under the Credit Facility
Estimated fair value of warrants												300,000
Short term convertible notes issued September 2012
Estimated future principal payments due under the Credit Facility
Fair value of beneficial conversion feature			300,000
Short term convertible notes issued September 2012 | Interest Expense.
Estimated future principal payments due under the Credit Facility
Amortization of debt discount and beneficial conversion	200,000				200,000	100,000
Short term convertible notes issued September 2012 | Warrant | Total
Estimated future principal payments due under the Credit Facility
Estimated fair value of warrants													100,000
Pfizer note
Debt
Interest rate (as a percent)															8.931%
Estimated future principal payments due under the Credit Facility
Aggregate principal amount															5,000,000
Outstanding principal amount														7,800,000
Accrued interest during period	300,000					600,000
Pfizer note | Series A-1 preferred stock
Estimated future principal payments due under the Credit Facility
Preferred stock, shares issued														6,750,000
Share price of preferred stock (in dollars per share)														$ 1.1560
Number of shares of preferred stock converted into shares of common stock							966,218
Credit Facility
Debt
Maximum borrowing capacity					20,000,000
Percentage of final payment equal to amount drawn under the Credit Facility					8.00%
Estimated future principal payments due under the Credit Facility
2015					638,000
2016					1,604,000
2017					1,709,000
2018					1,049,000
Total					5,000,000
Interest expense					300,000
Interest payments					100,000
Term A Loan
Debt
Maximum borrowing capacity					5,000,000
Period of consecutive equal monthly installments of principal and interest					36 months
Interest rate (as a percent)					6.40%
Term A Loan | Warrant
Debt
Warrants exercisable into stock (in shares)								8,230
Exercise price (in dollars per share)								$ 15.19
Unamortized discount								100,000
Term A Loan | Secured promissory notes
Debt
Proceeds from issuance of debt								5,000,000
Term B Loan
Debt
Maximum borrowing capacity					15,000,000
Remaining borrowing capacity					$ 15,000,000
Interest rate (as a percent)					6.40%
Reference rate					three month LIBOR
Number of business days prior to funding of new term loan					3 days
Interest rate margin (as a percent)					6.17%