Stockholders' Equity (Details Textual) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Stockholders' Equity (Textual) [Abstract]
Preferred stock, par value	$ 0.0001
Preferred stock, shares authorized	8,000,000
Exercise price of Warrants granted	$ 21,500
Issued warrants to purchase shares	390
Term of common stock warrants	5 years
Recognized weighted average period	2 years 9 months 18 days
Unamortized share-based compensation expense	$ 24,300,000
Share-based compensation expense	3,466,000
Common stock are reserved for issuance upon exercise of the warrants	390
Stockholders' Equity (Additional Textual) [Abstract]
Outstanding warrants	390
General and administrative
Stockholders' Equity (Textual) [Abstract]
Share-based compensation expense	3,070,000
Research and development
Stockholders' Equity (Textual) [Abstract]
Share-based compensation expense	396,000
Restricted Stock \| General and administrative
Stockholders' Equity (Textual) [Abstract]
Share-based compensation expense	9,000
Restricted Stock \| Research and development
Stockholders' Equity (Textual) [Abstract]
Share-based compensation expense	2,500
Restricted Stock Units
Stockholders' Equity (Textual) [Abstract]
Unamortized share-based compensation expense	597
Restricted Stock Units \| General and administrative
Stockholders' Equity (Textual) [Abstract]
Share-based compensation expense	52,000
Restricted Stock Units \| Research and development
Stockholders' Equity (Textual) [Abstract]
Share-based compensation expense	$ 57
Series C-1 Preferred
Stockholders' Equity (Textual) [Abstract]
Preferred stock, shares authorized	11,000
Preferred stock, shares issued	5,780
Preferred stock, shares outstanding	5,780
Series C-2 Preferred
Stockholders' Equity (Textual) [Abstract]
Preferred stock, shares authorized	22,000
Preferred stock, shares issued	500
Preferred stock, shares outstanding	500
Series D-1 Preferred
Stockholders' Equity (Textual) [Abstract]
Preferred stock, shares authorized	5,134
Preferred stock, shares issued	4,608
Preferred stock, shares outstanding	4,608
Series D-2 Preferred
Stockholders' Equity (Textual) [Abstract]
Preferred stock, shares authorized	10,868

Exercise price of warrants.

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Issued warrants to purchase shares.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Aggregate amount of each class of warrants or rights outstanding.

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Aggregate number of common shares reserved for future issuance.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Aggregate unrecognized cost of share-based awards, other than options, made to employees under an equity-based compensation plan, that have yet to vest.

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Aggregate unrecognized cost of option awards made to employees under a stock option plan or plans, that have yet to vest.

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Face amount or stated value per share of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer); generally not indicative of the fair market value per share.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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