Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parentheticals) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Issuance of Series D redeemable convertible preferred stock net of issuance costs of	$ 452us-gaap_PaymentsOfStockIssuanceCosts
Series C Preferred Stock [Member] \| Convertible Preferred Stock [Member]
Issuance of Series D redeemable convertible preferred stock net of discount associated with investors rights and obligations and issuance costs of $452	6,639
Issuance of Series D redeemable convertible preferred stock net of issuance costs of	452
Series D Preferred Stock [Member]
Issuance of Series D redeemable convertible preferred stock net of issuance costs of	$ 500

The cash outflow for cost incurred directly with the issuance of an equity security.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

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