Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Apr. 30, 2009
Dilutive Securities Adjustments [Line Items]
Net income attributable to Amkor	$ 20,633	$ 13,382
Income allocated to participating securities	(105)	(66)
Net income available to Amkor common stockholders — basic	20,528	13,316
Adjustment for dilutive securities on net income:
Net income reallocated to participating securities	3	66
Net income attributable to Amkor — diluted	21,438	17,408
Weighted average shares outstanding — basic	216,757	152,411
Effect of dilutive securities:
Stock options	109	18
Weighted average shares outstanding — diluted	235,497	235,087
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.09	$ 0.09
Diluted (in dollars per share)	$ 0.09	$ 0.07
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	$ 907	$ 4,026
Effect of dilutive securities:
6.0% convertible notes due 2014	18,631	82,658
Net income attributable to Amkor per common share:
Interest rate on convertible senior subordinated notes due April 2014	6.00%		6.00%