Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Dilutive Securities Adjustments [Line Items]
Net income attributable to Amkor	$ 56,812	$ 130,386	$ 109,296
Income allocated to participating securities	65	372	681
Net income available to Amkor common stockholders — basic	56,747	130,014	108,615
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Net income reallocated to participating securities	0	6	93
Net income attributable to Amkor — diluted	$ 56,747	$ 131,059	$ 118,148
Weighted average shares outstanding — basic	236,850	230,710	187,032
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Weighted average shares outstanding — diluted	237,170	236,731	235,330
Earnings Per Share, Basic and Diluted [Abstract]
Basic	$ 0.24	$ 0.56	$ 0.58
Diluted	$ 0.24	$ 0.55	$ 0.50
Stock Options and Restricted Share Awards [Member]
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Stock options and restricted share awards	320	712	21
Convertible Notes Due 2014 [Member]
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Interest on 6.0% convertible notes due 2014, net of tax	$ 0	$ 1,039	$ 9,440
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
6.0% convertible notes due 2014	0	5,309	48,277
Earnings Per Share, Basic and Diluted [Abstract]
Interest rate of convertible subordinated notes	6.00%	6.00%	6.00%