Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Amkor stockholders' equity:
Preferred stock designated Series A, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock designated Series A, shares authorized	10,000,000	10,000,000
Preferred stock designated Series A, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	197,758,000	197,709,000
Common stock, shares outstanding	152,427,000	152,397,000
Treasury stock, shares	45,331,000	45,312,000