Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Feb. 04, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-37774
Entity Registrant Name	AdvanSix Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-2525089
Entity Address, Address Line One	300 Kimball Drive
Entity Address, Address Line Two	Suite 101
Entity Address, City or Town	Parsippany
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	7054
City Area Code	973
Local Phone Number	526-1800
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	ASIX
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 821
Entity Common Stock, Shares Outstanding		28,141,203
Documents Incorporated by Reference	Part III: Proxy Statement for Annual Meeting of Stockholders to be held June 15, 2022.
Amendment Flag	false
Entity Central Index Key	0001673985
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY