Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit
Issuance of convertible preferred stock, issuance cost	$ 1,404kbio_StockIssuanceCosts

Amount of cost incurred directly with the issuance of a convertible preferred stock security during the reporting period.

No definition available.