Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net income (loss) available to Amkor common stockholders	$ (10,006)	$ (875)
Weighted-average number of common shares outstanding — basic	238,685	237,025
Weighted-average number of common shares outstanding — diluted	238,685	237,025
Net income (loss) attributable to Amkor per common share:
Basic (in dollars per share)	$ (0.04)	$ 0.00
Diluted (in dollars per share)	$ (0.04)	$ 0.00