Earnings Per Share - Calculation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Net income attributable to Amkor common stockholders, basic	$ 64,286	$ 124,778	$ 109,637	$ 295,441
Net income attributable to Amkor common stockholders, diluted	$ 64,286	$ 124,778	$ 109,637	$ 295,441
Weighted-average number of common shares outstanding - basic (in shares)	245,637	244,592	245,485	244,498
Effect of dilutive securities:
Share-based awards (in shares)	1,327	1,263	1,561	1,440
Weighted-average number of common shares outstanding - diluted (in shares)	246,964	245,855	247,046	245,938
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.26	$ 0.51	$ 0.45	$ 1.21
Diluted (in dollars per share)	$ 0.26	$ 0.51	$ 0.44	$ 1.20