Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Apr. 30, 2009
Dilutive Securities Adjustments [Line Items]
Net income attributable to Amkor	$ 47,097	$ 25,349	$ 117,251	$ 68,458
Income allocated to participating securities	(149)	(155)	(383)	(511)
Net income available to Amkor common stockholders — basic	46,948	25,194	116,868	67,947
Adjustment for dilutive securities on net income:
Net income reallocated to participating securities	0	7	9	78
Net income attributable to Amkor — diluted	46,948	26,108	117,916	76,558
Weighted average shares outstanding — basic	236,337	216,499	228,733	176,839
Effect of dilutive securities:
Stock options	1,172	12	841	13
Weighted average shares outstanding — diluted	237,509	235,143	236,672	235,119
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.20	$ 0.12	$ 0.51	$ 0.38
Diluted (in dollars per share)	$ 0.20	$ 0.11	$ 0.50	$ 0.33
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	$ 907	$ 1,039	$ 8,533
Effect of dilutive securities:
6.0% convertible notes due 2014	0	18,632	7,098	58,267
Net income attributable to Amkor per common share:
Interest rate on convertible notes due 2014	6.00%	6.00%	6.00%	6.00%	6.00%