Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 57,292	$ 60,458	$ 100,671	$ 166,520
Other comprehensive income (loss), net of tax:
Adjustments to unrealized components of defined benefit pension plans	(45)	15	(126)	263
Foreign currency translation	(6,611)	(969)	(2,664)	11,784
Total other comprehensive income (loss)	(6,656)	(954)	(2,790)	12,047
Comprehensive income	50,636	59,504	97,881	178,567
Comprehensive income attributable to non-controlling interests	(630)	(1,194)	(1,874)	(3,029)
Comprehensive income attributable to Amkor	$ 50,006	$ 58,310	$ 96,007	$ 175,538