Equity and Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 1,403,404	$ 1,217,536
Net income (loss)	(9,144)	(405)
Other comprehensive income (loss)	13,816	19,347
Issuance of stock through employee share-based compensation plans	145
Treasury stock acquired through surrender of shares for tax withholding	(210)	(119)
Share-based compensation	1,053	805
Subsidiary dividends paid to non-controlling interests	(135)	(135)
Ending balance	1,408,929	1,237,029
Amkor
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,383,588	1,200,286
Net income (loss)	(10,006)	(875)
Other comprehensive income (loss)	13,816	19,347
Issuance of stock through employee share-based compensation plans	145
Treasury stock acquired through surrender of shares for tax withholding	(210)	(119)
Share-based compensation	1,053	805
Subsidiary dividends paid to non-controlling interests	0	0
Ending balance	1,388,386	1,219,444
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	19,816	17,250
Net income (loss)	862	470
Other comprehensive income (loss)	0	0
Issuance of stock through employee share-based compensation plans	0
Treasury stock acquired through surrender of shares for tax withholding	0	0
Share-based compensation	0	0
Subsidiary dividends paid to non-controlling interests	(135)	(135)
Ending balance	$ 20,543	$ 17,585