Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Mar. 14, 2022	Jun. 30, 2021
Document And Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Entity File Number	001-37544
Entity Registrant Name	ARMATA PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	WA
Entity Tax Identification Number	91-1549568
Entity Address, Address Line One	4503 Glencoe Avenue
Entity Address, City or Town	Marina del Rey
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90292
City Area Code	858
Local Phone Number	829-0829
Title of 12(b) Security	Common Stock
Trading Symbol	ARMP
Security Exchange Name	NYSEAMER
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Interactive Data Current	Yes
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		30,727,091
Entity Public Float			$ 38.9
Entity Central Index Key	0000921114
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
ICFR Auditor Attestation Flag	false
Auditor Name	Ernst & Young, LLP
Auditor Firm ID	42
Auditor Location	San Diego, CA