Organization	12 Months Ended
Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	1. Organization MyoKardia, Inc. (the “Company”) is a clinical stage biopharmaceutical company pioneering a precision medicine approach to discover, develop and commercialize targeted therapies for the treatment of serious and neglected rare cardiovascular diseases. The Company’s initial focus is on the treatment of heritable cardiomyopathies, a group of rare, genetically-driven forms of heart failure that result from biomechanical defects in cardiac muscle contraction. The Company has used its precision medicine platform to generate an internal pipeline of four therapeutic programs for the chronic treatment of the two most common forms of heritable cardiomyopathy—hypertrophic cardiomyopathy, or HCM, and dilated cardiomyopathy, or DCM. The Company is currently enrolling subjects in a Phase 2 clinical trial of MYK-461, our product candidate for the treatment of HCM, and in a Phase 1 clinical trial of MYK-491, our product candidate for the treatment of DCM. In 2016, MYK-461 was granted Orphan Drug Designation by the U.S. Food and Drug Administration, or the FDA, for the treatment of symptomatic, obstructive hypertrophic cardiomyopathy (oHCM), a subset of HCM.The Company intends to expand its approach to deliver treatments with disease-modifying potential for patients with other forms of genetically-driven heart failure. The Company was incorporated on June 8, 2012 in Delaware and its corporate headquarters and operations are located in South San Francisco, California. Through December 31, 2016, the Company has financed its operations through an initial public offering, private placements of redeemable convertible preferred stock, payments received under the Collaboration Agreement, and a follow-on public offering. In April 2015, the Company had received net proceeds of $45.8 million from the sale of shares of its Series B redeemable convertible preferred stock. On October 29, 2015, the Company had completed its IPO of 6,253,125 shares of common stock at an offering price of $10.00 per share, resulting in net proceeds of approximately $55.6 million, after deducting underwriting discounts, commissions and offering costs. In October 2016, the Company completed a follow-on public offering and received net proceeds of $61.1 million from the sale of its common stock at an offering price of $15.00 per share. As of December 31, 2016, the Company had capital resources consisting of cash, cash equivalents, and investments of $151.9 million. The Company’s long-term success is dependent upon its ability to successfully develop, commercialize, and market its products, earn revenue, obtain capital when needed, and ultimately, to achieve profitable operations. However, if anticipated operating results are not achieved in future periods, management believes that planned expenditures may need to be reduced in order to extend the time period over which the then-available resources would be able to fund operations. The Company will need to raise additional capital to fully implement its business plan.

1. Organization

MyoKardia, Inc. (the “Company”) is a clinical stage biopharmaceutical company pioneering a precision medicine approach to discover, develop and commercialize targeted therapies for the treatment of serious and neglected rare cardiovascular diseases. The Company’s initial focus is on the treatment of heritable cardiomyopathies, a group of rare, genetically-driven forms of heart failure that result from biomechanical defects in cardiac muscle contraction. The Company has used its precision medicine platform to generate an internal pipeline of four therapeutic programs for the chronic treatment of the two most common forms of heritable cardiomyopathy—hypertrophic cardiomyopathy, or HCM, and dilated cardiomyopathy, or DCM. The Company is currently enrolling subjects in a Phase 2 clinical trial of MYK-461, our product candidate for the treatment of HCM, and in a Phase 1 clinical trial of MYK-491, our product candidate for the treatment of DCM. In 2016, MYK-461 was granted Orphan Drug Designation by the U.S. Food and Drug Administration, or the FDA, for the treatment of symptomatic, obstructive hypertrophic cardiomyopathy (oHCM), a subset of HCM.The Company intends to expand its approach to deliver treatments with disease-modifying potential for patients with other forms of genetically-driven heart failure. The Company was incorporated on June 8, 2012 in Delaware and its corporate headquarters and operations are located in South San Francisco, California.

Through December 31, 2016, the Company has financed its operations through an initial public offering, private placements of redeemable convertible preferred stock, payments received under the Collaboration Agreement, and a follow-on public offering. In April 2015, the Company had received net proceeds of $45.8 million from the sale of shares of its Series B redeemable convertible preferred stock. On October 29, 2015, the Company had completed its IPO of 6,253,125 shares of common stock at an offering price of $10.00 per share, resulting in net proceeds of approximately $55.6 million, after deducting underwriting discounts, commissions and offering costs. In October 2016, the Company completed a follow-on public offering and received net proceeds of $61.1 million from the sale of its common stock at an offering price of $15.00 per share. As of December 31, 2016, the Company had capital resources consisting of cash, cash equivalents, and investments of $151.9 million.

The Company’s long-term success is dependent upon its ability to successfully develop, commercialize, and market its products, earn revenue, obtain capital when needed, and ultimately, to achieve profitable operations. However, if anticipated operating results are not achieved in future periods, management believes that planned expenditures may need to be reduced in order to extend the time period over which the then-available resources would be able to fund operations. The Company will need to raise additional capital to fully implement its business plan.