Equity and Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance			$ 964,940	$ 666,794
Net income	48,170	26,004	119,759	70,099
Other comprehensive income (loss)	(9,727)	2,533	(17,223)	(4,401)
Issuance of stock through employee share-based compensation plans			5,826
Treasury stock acquired through surrender of shares for tax withholding			(1,348)	(234)
Share-based compensation expense			2,766	2,065
Conversion of debt to common stock			56,350
Exchange of debt for common stock				195,034
Equity, Ending balance	1,131,070	929,357	1,131,070	929,357
Amkor [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance			953,740	657,955
Net income			117,251	68,458
Other comprehensive income (loss)			(17,223)	(4,401)
Issuance of stock through employee share-based compensation plans			5,826
Treasury stock acquired through surrender of shares for tax withholding			(1,348)	(234)
Share-based compensation expense			2,766	2,065
Conversion of debt to common stock			56,350
Exchange of debt for common stock				195,034
Equity, Ending balance	1,117,362	918,877	1,117,362	918,877
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance			11,200	8,839
Net income			2,508	1,641
Other comprehensive income (loss)			0	0
Issuance of stock through employee share-based compensation plans			0
Treasury stock acquired through surrender of shares for tax withholding			0	0
Share-based compensation expense			0	0
Conversion of debt to common stock			0
Exchange of debt for common stock				0
Equity, Ending balance	$ 13,708	$ 10,480	$ 13,708	$ 10,480