CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Total Amkor Stockholders’ Equity	Common Stock	Additional Paid- In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interest in Subsidiaries
Balance at beginning of period, common stock (in shares) at Dec. 31, 2021			290,466
Balance at beginning of period at Dec. 31, 2021	$ 2,972,546	$ 2,942,276	$ 290	$ 1,977,134	$ 1,163,939	$ 19,978	$ (219,065)	$ 30,270
Balance at beginning of period, treasury stock (in shares) at Sep. 30, 2022							(46,155)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	603,154	601,522			601,522			1,632
Other comprehensive income (loss)	(33,561)	(33,561)				(33,561)
Treasury stock acquired through surrender of shares for tax withholding (in shares)							(4)
Treasury stock acquired through surrender of shares for tax withholding	(82)	(82)					$ (82)
Issuance of stock through share-based compensation plans (in shares)			500
Issuance of stock through share-based compensation plans	3,201	3,201	$ 1	3,200
Share-based compensation	10,711	10,711		10,711
Cash Dividends declared	(36,721)	(36,721)			(36,721)
Subsidiary dividends to non-controlling interests	(405)							(405)
Balance at end of period, common stock (in shares) at Sep. 30, 2022			290,966
Balance at end of period at Sep. 30, 2022	3,518,843	3,487,346	$ 291	1,991,045	1,728,740	(13,583)	$ (219,147)	31,497
Balance at end of period, treasury stock (in shares) at Dec. 31, 2021							(46,151)
Balance at beginning of period, common stock (in shares) at Jun. 30, 2022			290,788
Balance at beginning of period at Jun. 30, 2022	3,227,550	3,196,295	$ 291	1,985,992	1,434,906	(5,747)	$ (219,147)	31,255
Balance at beginning of period, treasury stock (in shares) at Sep. 30, 2022							(46,155)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	306,457	306,081			306,081			376
Other comprehensive income (loss)	(7,836)	(7,836)				(7,836)
Issuance of stock through share-based compensation plans (in shares)			178
Issuance of stock through share-based compensation plans	1,460	1,460		1,460
Share-based compensation	3,593	3,593		3,593
Cash Dividends declared	(12,247)	(12,247)			(12,247)
Subsidiary dividends to non-controlling interests	(134)							(134)
Balance at end of period, common stock (in shares) at Sep. 30, 2022			290,966
Balance at end of period at Sep. 30, 2022	$ 3,518,843	3,487,346	$ 291	1,991,045	1,728,740	(13,583)	$ (219,147)	31,497
Balance at end of period, treasury stock (in shares) at Jun. 30, 2022							(46,155)
Balance at beginning of period, common stock (in shares) at Dec. 31, 2022	245,091		291,249
Balance at beginning of period at Dec. 31, 2022	$ 3,699,701	3,668,752	$ 291	1,996,344	1,874,644	16,699	$ (219,226)	30,949
Balance at beginning of period, treasury stock (in shares) at Sep. 30, 2023	(46,269)						(46,269)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 243,119	242,251			242,251			868
Other comprehensive income (loss)	(14,860)	(14,860)				(14,860)
Treasury stock acquired through surrender of shares for tax withholding (in shares)							(111)
Treasury stock acquired through surrender of shares for tax withholding	(2,839)	(2,839)					$ (2,839)
Issuance of stock through share-based compensation plans (in shares)			784
Issuance of stock through share-based compensation plans	2,285	2,285	$ 1	2,284
Share-based compensation	6,398	6,398		6,398
Cash Dividends declared	(55,299)	(55,299)			(55,299)
Subsidiary dividends to non-controlling interests	$ (406)							(406)
Balance at end of period, common stock (in shares) at Sep. 30, 2023	245,764		292,033
Balance at end of period at Sep. 30, 2023	$ 3,878,099	3,846,688	$ 292	2,005,026	2,061,596	1,839	$ (222,065)	31,411
Balance at end of period, treasury stock (in shares) at Dec. 31, 2022	(46,158)						(46,158)
Balance at beginning of period, common stock (in shares) at Jun. 30, 2023			291,958
Balance at beginning of period at Jun. 30, 2023	$ 3,762,859	3,732,150	$ 292	2,005,055	1,947,420	1,432	$ (222,049)	30,709
Balance at beginning of period, treasury stock (in shares) at Sep. 30, 2023	(46,269)						(46,269)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 133,451	132,614			132,614			837
Other comprehensive income (loss)	407	407				407
Treasury stock acquired through surrender of shares for tax withholding	(16)	(16)					$ (16)
Issuance of stock through share-based compensation plans (in shares)			75
Issuance of stock through share-based compensation plans	360	360		360
Share-based compensation	(389)	(389)		(389)
Cash Dividends declared	(18,438)	(18,438)			(18,438)
Subsidiary dividends to non-controlling interests	$ (135)							(135)
Balance at end of period, common stock (in shares) at Sep. 30, 2023	245,764		292,033
Balance at end of period at Sep. 30, 2023	$ 3,878,099	$ 3,846,688	$ 292	$ 2,005,026	$ 2,061,596	$ 1,839	$ (222,065)	$ 31,411
Balance at end of period, treasury stock (in shares) at Jun. 30, 2023							(46,269)