Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (22,668)	$ 10,195
Other comprehensive income (loss), net of tax:
Adjustments to unrealized components of defined benefit pension plans	(132)	(39)
Foreign currency translation	(2,224)	15,091
Total other comprehensive income (loss)	(2,356)	15,052
Comprehensive income (loss)	(25,024)	25,247
Comprehensive income attributable to non-controlling interests	(211)	(651)
Comprehensive income (loss) attributable to Amkor	$ (25,235)	$ 24,596