Earnings Per Share Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Dilutive Securities Adjustments [Line Items]
Net income attributable to Amkor	$ 9,578	$ 49,521	$ 38,359	$ 70,154
Income allocated to participating securities	(21)	(184)	(85)	(269)
Net income available to Amkor common stockholders — basic	9,557	49,337	38,274	69,885
Adjustment for dilutive securities on net income:
Net income reallocated to participating securities	0	3	0	9
Net income attributable to Amkor — diluted	$ 9,557	$ 49,472	$ 38,274	$ 70,933
Weighted average shares outstanding — basic	236,840	232,891	236,774	224,868
Effect of dilutive securities:
Weighted average shares outstanding — diluted	237,321	236,872	237,366	236,182
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.04	$ 0.21	$ 0.16	$ 0.31
Diluted (in dollars per share)	$ 0.04	$ 0.21	$ 0.16	$ 0.30
Convertible Senior Subordinated Notes Due April 2014 [Member]
Adjustment for dilutive securities on net income:
Interest on 6.0% convertible notes due 2014, net of tax	$ 0	$ 132	$ 0	$ 1,039
Effect of dilutive securities:
6.0% convertible notes due 2014	0	2,866	0	10,705
Net income attributable to Amkor per common share:
Interest rate on convertible senior subordinated notes due April 2014	0.00%	6.00%	0.00%	6.00%
Stock Options Dilutive Effect [Member]
Effect of dilutive securities:
Stock options	481	1,115	592	609