Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 19, 2020	Jun. 28, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-38311
Entity Registrant Name	Denali Therapeutics Inc.
Entity Central Index Key	0001714899
Document Fiscal Year Focus	2019
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-3872213
Entity Address, Address Line One	161 Oyster Point Blvd
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	866-8548
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	DNLI
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 715.6
Entity Common Stock, Shares Outstanding		105,423,277
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement relating to the registrant’s 2019 Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. Such Definitive Proxy Statement will be filed with the Securities and Exchange Commission within 120 days after the end of the registrant’s 2019 fiscal year ended December 31, 2019.