Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Apr. 30, 2009
Dilutive Securities Adjustments [Line Items]
Net income attributable to Amkor	$ 29,727	$ 581	$ 43,109	$ 12,355
Income allocated to participating securities	(251)	(2)	(374)	(33)
Net income available to Amkor common stockholders	29,476	579	42,735	12,322
Adjustment for dilutive securities on net income:
Net income reallocated to participating securities	58	2	80	33
Net income attributable to Amkor — diluted	33,143	581	50,441	12,355
Weighted average shares outstanding — basic	160,886	165,956	156,672	166,911
Effect of dilutive securities:
Stock options and restricted share awards	10	53	14	101
Weighted average shares outstanding — diluted	235,111	166,009	235,099	167,012
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.18	$ 0.00	$ 0.27	$ 0.07
Diluted (in dollars per share)	$ 0.14	$ 0.00	$ 0.21	$ 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	$ 3,609	$ 0	$ 7,626	$ 0
Effect of dilutive securities:
6.0% convertible notes due 2014	74,215	0	78,413	0
Net income attributable to Amkor per common share:
Interest rate on convertible senior subordinated notes due April 2014	6.00%		6.00%		6.00%