Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 1,326,150	$ 1,152,616
Cost of sales	1,060,616	963,708
Gross profit	265,534	188,908
Selling, general and administrative	76,768	72,582
Research and development	44,318	32,253
Total operating expenses	121,086	104,835
Operating income	144,448	84,073
Interest expense	12,673	17,045
Other (income) expense, net	89	(2,315)
Total other expense, net	12,762	14,730
Income before taxes	131,686	69,343
Income tax expense	11,667	4,846
Net income	120,019	64,497
Net income attributable to non-controlling interests	(210)	(608)
Net income attributable to Amkor	$ 119,809	$ 63,889
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.49	$ 0.27
Diluted (in dollars per share)	$ 0.49	$ 0.26
Shares used in computing per common share amounts:
Basic (in shares)	243,267	240,919
Diluted (in shares)	245,129	241,333