Earnings Per Share - Calculation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net income attributable to Amkor common stockholders, basic	$ 132,614	$ 306,081	$ 242,251	$ 601,522
Net income attributable to Amkor common stockholders, diluted	$ 132,614	$ 306,081	$ 242,251	$ 601,522
Weighted-average number of common shares outstanding - basic (in shares)	245,740	244,744	245,571	244,581
Effect of dilutive securities:
Share-based awards (in shares)	1,389	1,350	1,509	1,434
Weighted-average number of common shares outstanding - diluted (in shares)	247,129	246,094	247,080	246,015
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.54	$ 1.25	$ 0.99	$ 2.46
Diluted (in dollars per share)	$ 0.54	$ 1.24	$ 0.98	$ 2.45