Debt (Details) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) item	Apr. 30, 2013 USD ($)	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 USD ($)	Dec. 31, 2007 $ / shares
Line of Credit Facility [Line Items]
Royalty and interest expense				$ 1,177	$ 1,202	$ 3,391	$ 2,947
Exercise price of warrants (in dollars per share) | $ / shares								$ 0.0978
Repayments of equipment financing						5,850	1,798
Secured Loan Arrangement
Line of Credit Facility [Line Items]
Borrowing capacity			$ 40,000
Borrowings			$ 20,000
Base interest rate (as a percent)			1.00%
Spread on base interest rate (as a percent)			8.00%
Interest rate floor (as a percent)			9.00%
Royalty payment percentage owed on fiscal year revenues up to threshold			1.00%
Revenue threshold amount for determination of royalty payment percentage			$ 50,000
Royalty payment percentage owed on fiscal year revenues in excess of threshold			1.50%
Interest expense						1,400	1,400
Royalty expenses						$ 1,800	$ 1,400
Effective interest and royalty yield (as a percent)						21.10%
Number of shares of common stock that may be called by warrants | shares	376,691			376,691		376,691
Exercise price of warrants (in dollars per share) | $ / shares	$ 2.3229			$ 2.3229		$ 2.3229
Prepayment premium (as a percent)	10.00%			10.00%		10.00%
Minimum liquidity required under debt covenants	$ 5,000			$ 5,000		$ 5,000
Line Of Credit-UBS
Line of Credit Facility [Line Items]
Borrowing capacity	$ 50,000			$ 50,000		$ 50,000
Effective interest rate (as a percent)	0.84%			0.84%		0.84%
Line Of Credit-UBS | 30-day LIBOR
Line of Credit Facility [Line Items]
Spread on variable rate (as a percent)	0.65%
Equipment Financing Facility
Line of Credit Facility [Line Items]
Borrowing capacity			$ 5,000
Borrowings		$ 5,900
Effective interest rate (as a percent)		6.35%	7.35%
Number of payment installments | item		30
Repayments of equipment financing	$ 4,100
Equipment Financing Facility | 30-day LIBOR
Line of Credit Facility [Line Items]
Spread on reference rate (as a percent)			2.50%
Spread on variable rate (as a percent)			4.10%
Equipment Financing Facility | Prime
Line of Credit Facility [Line Items]
Spread on variable rate (as a percent)		3.10%