Equity and Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance		$ 1,217,536		$ 1,217,536	$ 1,129,449
Net income	$ 5,366		$ 7,950	4,961	35,464
Other comprehensive income	26,978	19,347	(5,213)	46,325	(3,953)
Issuance of stock through employee share-based compensation plans				60	656
Treasury stock acquired through surrender of shares for tax withholding				(238)	(427)
Share-based compensation expense				1,626	2,248
Subsidiary dividends paid to non-controlling interests				(270)	0
Equity, Ending balance	1,270,000		1,163,437	1,270,000	1,163,437
Amkor [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance		1,200,286		1,200,286	1,114,748
Net income				3,838	33,925
Other comprehensive income				46,325	(3,953)
Issuance of stock through employee share-based compensation plans				60	656
Treasury stock acquired through surrender of shares for tax withholding				(238)	(427)
Share-based compensation expense				1,626	2,248
Subsidiary dividends paid to non-controlling interests				0
Equity, Ending balance	1,251,897		1,147,197	1,251,897	1,147,197
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance		$ 17,250		17,250	14,701
Net income				1,123	1,539
Other comprehensive income				0	0
Issuance of stock through employee share-based compensation plans				0	0
Treasury stock acquired through surrender of shares for tax withholding				0	0
Share-based compensation expense				0	0
Subsidiary dividends paid to non-controlling interests				(270)
Equity, Ending balance	$ 18,103		$ 16,240	$ 18,103	$ 16,240