2.4.0.80000 - Document - Document and Entity Informationtruefalsefalse1false falsefalseD2012http://www.sec.gov/CIK0001436304duration2012-01-01T00:00:002012-12-31T00:00:002false falsefalseI2012SOhttp://www.sec.gov/CIK0001436304instant2013-02-25T00:00:000001-01-01T00:00:00SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli03false USDfalsefalse$I2012PFhttp://www.sec.gov/CIK0001436304instant2012-06-29T00:00:000001-01-01T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 1kyth_DocumentAndEntityInformationAbstractkyth_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Document and Entity Information2false 2dei_EntityRegistrantNamedei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00KYTHERA BIOPHARMACEUTICALS INCfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:normalizedStringItemTypenormalizedstringThe exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 false0Entity Registrant Name3false 2dei_EntityCentralIndexKeydei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse000001436304falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsedei:centralIndexKeyItemTypenaA unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. 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For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.No definition available.false0Document Period End Date6false 2dei_AmendmentFlagdei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00truefalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:booleanItemTypenaIf the value is true, then the document is an amendment to previously-filed/accepted document.No definition available.false0Amendment Flag7false 2dei_AmendmentDescriptiondei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00EXPLANATORY NOTE We are filing this Amendment No. 1 on Form 10-K/A (the "Amended Filing") to our Annual Report on Form 10-K for the year ended December 31, 2012 originally filed with the Securities and Exchange Commission ("SEC") on March 26, 2013 (the "Original Filing") to correct the presentation of basic and diluted weighted average shares outstanding and the related net income (loss) per share for the periods from December 31, 2008 through December 31, 2012, and to update the related disclosures found in Part II-Item 6. Selected Financial Data and Item 8. Financial Statements and Supplementary Data. Description of the Restatement We are filing this amendment to correct the previously reported basic and diluted net income (loss) per share amounts for periods from December 31, 2008 through December 31, 2012. Although net income (loss) was correct as reported, basic and diluted net income (loss) per share was incorrectly computed. Basic and diluted net income (loss) per share is calculated by dividing net income (loss) for the period by the basic and diluted weighted average number of shares outstanding during that period. In the restated periods, preferred shares issued prior to the Company's initial public offering in October 2012 were inappropriately included in the weighted average shares outstanding used to calculate basic and diluted net income (loss) per share from their date of issuance, rather than from the date of actual conversion to common shares as a result of the Company's initial public offering. Similarly, the effects of the assumed conversion of the preferred shares should have only been included in the diluted net income per share prior to actual conversion to the extent that the impact would have been dilutive. For more information regarding the calculation of net income (loss) per common share, please refer to Note 2, "Summary of Significant Accounting Policies-Basic and Dilutive Net Loss per Common Share." For more information on our evaluation of this restatement of our disclosure controls and procedures, please refer to Item 9A, "Controls and Procedures." The corrections have no impact on the Company's net income (loss) reported in the statement of operations and comprehensive loss, balance sheets, or the statements of cash flows or stockholders' equity (deficit) for any of the above mentioned periods. Items Amended in This Filing For the convenience of the reader, this Amended Filing sets forth the Original Filing, as modified and superseded where necessary to reflect the restatement. The following items have been amended as a result of, and to reflect, the restatement: Part II-Item 6. Selected Financial Data; Part II-Item 8. Financial Statements and Supplementary Data; Part II-Item 9A. Controls and Procedures; and Part IV-Item 15. Exhibits, Financial Statement Schedules. In accordance with applicable SEC rules, this Amended Filing includes new certifications as required by Rule 12b-15 under the Securities and Exchange Act of 1934 ("Exchange Act") from our Chief Executive Officer and Chief Financial Officer dated as of the date of filing of this Amended Filing. Except for the items noted above, no other information included in the Original Filing is being amended or updated by this Amended Filing. This Amended Filing continues to describe the conditions as of the date of the Original Filing and, except as contained herein, we have not updated or modified the disclosures contained in the Original Filing. 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This information should be based on the registrant's current or most recent filing containing the related disclosure.No definition available.false0Entity Current Reporting Status12false 2dei_EntityFilerCategorydei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Non-accelerated Filerfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsedei:filerCategoryItemTypestringIndicate whether the registrant is one of the following: (1) Large Accelerated Filer, (2) Accelerated Filer, (3) Non-accelerated Filer, (4) Smaller Reporting Company (Non-accelerated) or (5) Smaller Reporting Accelerated Filer. Definitions of these categories are stated in Rule 12b-2 of the Exchange Act. 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The public float should be reported on the cover page of the registrants form 10K.No definition available.false2Entity Public Float14false 2dei_EntityCommonStockSharesOutstandingdei_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2truefalsefalse1833238218332382falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:sharesItemTypesharesIndicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. 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