Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Apr. 30, 2009
Dilutive Securities Adjustments [Line Items]
Net income attributable to Amkor	$ 25,349	$ 22,317	$ 68,458	$ 34,672
Income allocated to participating securities	(155)	(55)	(511)	(81)
Net income available to Amkor common stockholders	25,194	22,262	67,947	34,591
Adjustment for dilutive securities on net income:
Net income reallocated to participating securities	7	55	78	81
Net income attributable to Amkor — diluted	26,108	26,343	76,558	46,749
Weighted average shares outstanding — basic	216,499	154,365	176,839	162,699
Effect of dilutive securities:
Stock options and restricted share awards	12	37	13	74
Weighted average shares outstanding — diluted	235,143	237,060	235,119	245,431
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.12	$ 0.14	$ 0.38	$ 0.21
Diluted (in dollars per share)	$ 0.11	$ 0.11	$ 0.33	$ 0.19
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	$ 8,533	$ 12,077
Effect of dilutive securities:
6.0% convertible notes due 2014	18,632	82,658	58,267	82,658
Net income attributable to Amkor per common share:
Interest rate on convertible senior subordinated notes due April 2014	6.00%		6.00%		6.00%