Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 25, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
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	07054
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 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 Common Stock, Shares Outstanding		27,912,355
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001673985
Amendment Flag	false