CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Consolidated Balance Sheets
Convertible senior notes, interest rate (as a percent)	2.50%	2.50%
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	2,000,000us-gaap_PreferredStockSharesAuthorized	2,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	58,750,000us-gaap_CommonStockSharesAuthorized	58,750,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	30,531,621us-gaap_CommonStockSharesIssued	25,599,550us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	30,531,621us-gaap_CommonStockSharesOutstanding	25,599,550us-gaap_CommonStockSharesOutstanding

Face amount or stated value per share of common stock.

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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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Contractual interest rate for funds borrowed, under the debt agreement.

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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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