Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 23, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	000-29472
Entity Registrant Name	AMKOR TECHNOLOGY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	23-1722724
Entity Address, Address Line One	2045 East Innovation Circle
Entity Address, City or Town	Tempe
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85284
City Area Code	480
Local Phone Number	821-5000
Entity Filer Category	Large Accelerated Filer
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	AMKR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		242,446,149
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001047127