Equity and Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance	$ 1,225,133	$ 1,130,936
Net income (loss)	(405)	29,697
Other comprehensive income	19,888	1,238
Issuance of stock through employee share-based compensation plans		574
Treasury stock acquired through surrender of shares for tax withholding	(119)	(230)
Share-based compensation expense	805	1,369
Payments of Ordinary Dividends, Noncontrolling Interest	(135)	0
Equity, Ending balance	1,245,167	1,163,584
Amkor [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance	1,207,883	1,116,235
Net income (loss)	(875)	28,781
Other comprehensive income	19,888	1,238
Issuance of stock through employee share-based compensation plans		574
Treasury stock acquired through surrender of shares for tax withholding	(119)	(230)
Share-based compensation expense	805	1,369
Payments of Ordinary Dividends, Noncontrolling Interest	0
Equity, Ending balance	1,227,582	1,147,967
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance	17,250	14,701
Net income (loss)	470	916
Other comprehensive income	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 expense	0	0
Payments of Ordinary Dividends, Noncontrolling Interest	(135)
Equity, Ending balance	$ 17,585	$ 15,617