Common Stock and Preferred Stock (Tables)

9 Months Ended

Sep. 30, 2013

Equity [Abstract]

Company's Outstanding Convertible Preferred Stock Warrants

The following information summarizes the Company’s outstanding convertible preferred stock warrants:

Preferred Stock Warrants		Expiry Date	Number of shares		Fair Value at December 31, 2011		Fair Value at December 31, 2012
Preferred Stock	Issue Date
			(In thousands, except share amounts)
Series B	October 2007	October 2014		2,458	$	4	$	7
Series B	April 2008	October 2014		2,233		4		7
Series C	November 2010	November 2017		5,918		21		24
Series C	October 2011	November 2018		10,175		40		44
Series D	November 2011	November 2018		486,002		2,428		2,725
Series D	March 2012	March 2022		44,389		—		299
Series D	December 2012	December 2022		32,551		—		225
Series E	December 2012	December 2022		20,837		—		201
				604,563	$	2,497	$	3,532

Carrying Value of the Warrants to Purchase Shares of the Company's Preferred Stock

The following information summarizes the carrying value of the warrants to purchase shares of the Company’s preferred stock:

	(In thousands)
Balance at December 31, 2009	$	27
Issuance of preferred stock warrants		30
Warrant revaluation		(15	)
Balance at December 31, 2010		42
Issuance of preferred stock warrants		2,528
Warrant revaluation		(73	)
Balance at December 31, 2011		2,497
Issuance of preferred stock warrants		648
Warrant revaluation		387
Balance at December 31, 2012	$	3,532