Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2012

Summary of Significant Accounting Policies

Schedule of fair value of the financial assets and liabilities

			Fair Value Measurements at December 31, 2010
	Total Carrying Value at December 31, 2010		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash and cash equivalents	$	23,740	$	23,740	$	—	$	—
Marketable securities		8,964		1,024		7,940		—
Marketable securities — restricted		261		—		261		—
Cash and cash equivalents — restricted(1)		1,453		1,453		—		—
Total assets at fair value	$	34,418	$	26,217	$	8,201	$	—

(1)  Included in assets of discontinued operations at December 31, 2010.

			Fair Value Measurements at December 31, 2011
	Total Carrying Value at December 31, 2011		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Assets:
Cash and cash equivalents	$	48,544	$	48,544	$	—	$	—
Marketable securities — restricted		245		—		245		—
Total assets at fair value	$	48,789	$	48,544	$	245	$	—
Liabilities:
Warrant liability	$	697	$	—	$	—	$	697

			Fair Value Measurements at September 30, 2012
	Total Carrying Value at September 30, 2012		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands) (unaudited)
Assets:
Cash and cash equivalents	$	23,412	$	23,412	$	—	$	—
Marketable securities		37,256		—		37,256		—
Marketable securities — restricted		275		—		275		—
Marketable securities — noncurrent		1,804		—		1,804		—
Total assets at fair value	$	62,747	$	23,412	$	39,335	$	—
Liabilities:
Warrant liability	$	1,463	$	—	$	—	$	1,463

Schedule of assumptions used to calculate fair value of stock warrant liability using Monte-Carlo simulation on a Black-Scholes lattice model

Exercise Price	$4 - $5 per share
Volatility	80%
Stock Price as of September 30, 2012	$11.55 per share
Term	8.3 - 9.3 years
Dividend Yield	0.0%
Risk-Free Rate	1.4% - 1.5%

Schedule of the entity's common stock warrant liability

	Year Ended December 31, 2011 and Nine Months Ended September 30, 2012
	(in thousands)
Balance at December 31, 2010	$	—
Issuance of Series A Preferred Stock warrants		612
Changes in fair value of warrants included in earnings		85
Balance at December 31, 2011		697
Changes in fair value of warrants included in earnings (unaudited)		766
Balance at September 30, 2012 (unaudited)	$	1,463

Schedule of average useful lives used to compute depreciation and amortization

Computer equipment	3 years
Software	3 years
Lab and office equipment	5 years
Furniture	7 years
Leasehold Improvements	Shorter of lease term or useful life
Manufacturing equipment	5 - 10 years

Schedule of common stock equivalents excluded in the calculation of diluted earnings (loss) per share

	Year Ended December 31,						Nine Months Ended September 30,
	2009		2010		2011		2011		2012
							(unaudited)
Series A Preferred Stock		—		12,249,998		12,249,998		12,249,998		5,409,671
Warrants to purchase Series A Preferred Stock/Common Stock		—		—		143,749		26,227		71,662
Stock options, Non-Vested Stock Options and ESPP Awards		—		767,428		598,109		429,442		290,029