Cover Page	May 18, 2020
Cover [Abstract]
Title of 12(b) Security	Common Stock, par value $0.001 per share
Entity Central Index Key	0001576263
Amendment Flag	false
Document Type	8-K
Document Period End Date	May 18, 2020
Entity Registrant Name	Mirati Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity File Number	001-35921
Entity Tax Identification Number	46-2693615
Entity Address, Address Line One	9393 Towne Centre Drive, Suite 200
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	332-3410
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Entity Emerging Growth Company	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Trading Symbol	MRTX
Security Exchange Name	NASDAQ