Subsequent Events	6 Months Ended
Jun. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	12. Subsequent Events On July 18, 2019, the Company announced an agreement with Sanofi to reacquire the U.S. royalty rights to mavacamten and MYK-224 for $80 million, of which $50 million was paid immediately and $30 million was transferred to escrow to be paid by June 30, 2020. The agreement also required the Company to pay $4.3 million to Sanofi for certain of its assets related to the MYK-491 program. All amounts were paid in July 2019. Neither the Company nor Sanofi have further obligations under the agreement that would prevent the payment of the escrowed amount. As a result of the agreement, there are no further financial rights or obligations between the Company and Sanofi except for the final settlement of the cost sharing arrangement described in Note 3, which will occur in the third quarter of 2019.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-URI http://asc.fasb.org/topic&trid=2122774

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