Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Dilutive Securities Adjustments [Line Items]
Net income attributable to Amkor	$ 13,382	$ 11,774
Net income allocated to participating securities	(66)	(38)
Net income available to Amkor common stockholders	13,316	11,736
Adjustment for dilutive securities on net income:
Net income allocated to participating securities	66	38
Net income attributable to Amkor-diluted	17,408	15,800
Weighted average shares outstanding-basic (in shares)	152,411	167,866
Effect of dilutive securities:
Stock options and restricted share awards (in shares)	18	164
Weighted average shares outstanding-diluted (in shares)	235,087	250,688
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.09	$ 0.07
Diluted (in dollars per share)	$ 0.07	$ 0.06
Convertible Notes Due 2014 [Member]
Adjustment for dilutive securities on net income:
Interest on 6.0% convertible notes due 2014, net of tax	$ 4,026	$ 4,026
Effect of dilutive securities:
6.0% convertible notes due 2014 (in shares)	82,658	82,658
Net income attributable to Amkor per common share:
Debt interest rate	6.00%