Document And Entity Information
Nov. 12, 2019
Cover [Abstract]  
Entity Registrant Name Allakos Inc.
Document Type 8-K
Amendment Flag false
Entity Central Index Key 0001564824
Document Period End Date Nov. 12, 2019
Entity Emerging Growth Company true
Entity Ex Transition Period true
Entity File Number 001-38582
Entity Incorporation, State or Country Code DE
Entity Tax Identification Number 45-4798831
Entity Address, Address Line One 975 Island Drive
Entity Address, Address Line Two Suite 201
Entity Address, City or Town Redwood City
Entity Address, State or Province CA
Entity Address, Postal Zip Code 94065
City Area Code 650
Local Phone Number 597-5002
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of Each Class Common Stock, par value $0.001
Trading Symbol ALLK
Name of Each Exchange on Which Registered NASDAQ