Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Redeemable common stock, par value	$ 0.0001	$ 0.0001
Redeemable common stock, shares outstanding	0	1,344,236
Series A Convertible Preferred Stock, par value	$ 0.0001	$ 0.0001
Series A Convertible Preferred Stock, shares authorized	25,000,000us-gaap_PreferredStockSharesAuthorized	25,000,000us-gaap_PreferredStockSharesAuthorized
Series A Convertible Preferred Stock, shares issued	0us-gaap_PreferredStockSharesIssued	19,284,113us-gaap_PreferredStockSharesIssued
Series A Convertible Preferred Stock, shares outstanding	0us-gaap_PreferredStockSharesOutstanding	19,284,113us-gaap_PreferredStockSharesOutstanding
Series A Convertible Preferred Stock, liquidation preference		$ 86,200
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000us-gaap_CommonStockSharesAuthorized	165,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	81,905,325us-gaap_CommonStockSharesIssued	53,757,437us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	81,905,325us-gaap_CommonStockSharesOutstanding	53,757,437us-gaap_CommonStockSharesOutstanding

Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Value of the difference between preference in liquidation and the par or stated values of the preferred shares.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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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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Per share amount of par value or stated value of stock classified as temporary equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable.

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