Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Convertible notes, accrued interest payable (in Dollars)	$ 0us-gaap_InterestPayableCurrent	$ 112us-gaap_InterestPayableCurrent
Preferred stock, par value (in Dollars per share)	$ 0.001	$ 0
Preferred stock, shares authorized	10,000,000us-gaap_PreferredStockSharesAuthorized	0us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Preferred stock,shares outstanding	0us-gaap_PreferredStockSharesOutstanding	0us-gaap_PreferredStockSharesOutstanding
Common stock, par value (in Dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000us-gaap_CommonStockSharesAuthorized	100,370,203us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	16,448,455us-gaap_CommonStockSharesIssued	239,905us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	16,448,455us-gaap_CommonStockSharesOutstanding	239,905us-gaap_CommonStockSharesOutstanding
Series A Preferred Stock [Member]
Redeemable convertible preferred stock, par value (in Dollars per share)	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	0	22,638,465
Redeemable convertible preferred stock, shares issued	0	22,638,465
Redeemable convertible preferred stock shares outstanding	0	22,638,465
Redeemable convertible preferred stock, aggregate liquidation preference (in Dollars)	0	22,638
Series A-1 Preferred Stock [Member]
Redeemable convertible preferred stock, par value (in Dollars per share)	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	0	10,909,091
Redeemable convertible preferred stock, shares issued	0	10,909,091
Redeemable convertible preferred stock shares outstanding	0	10,909,091
Redeemable convertible preferred stock, aggregate liquidation preference (in Dollars)	0	12,000
Series B Preferred Stock [Member]
Redeemable convertible preferred stock, par value (in Dollars per share)	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	0	20,754,461
Redeemable convertible preferred stock, shares issued	0	20,754,461
Redeemable convertible preferred stock shares outstanding	0	20,754,461
Redeemable convertible preferred stock, aggregate liquidation preference (in Dollars)	0	23,867
Series C Preferred Stock [Member]
Redeemable convertible preferred stock, par value (in Dollars per share)	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	0	17,550,758
Redeemable convertible preferred stock, shares issued	0	13,202,932
Redeemable convertible preferred stock shares outstanding	0	13,202,932
Redeemable convertible preferred stock, aggregate liquidation preference (in Dollars)	0	15,183
Series D Preferred Stock [Member]
Redeemable convertible preferred stock, par value (in Dollars per share)	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	0	0
Redeemable convertible preferred stock, shares issued	0	0
Redeemable convertible preferred stock shares outstanding	0	0
Redeemable convertible preferred stock, aggregate liquidation preference (in Dollars)	$ 0	$ 0

Face amount or stated value per share of common stock.

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