Pension and Severance Plans Textuals (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Non-current (Pension and severance obligations)	$ 153,027,000		$ 152,673,000
Korean Severance Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Provision of Severance Benefits	5,100,000	5,600,000
Current (Accrued expenses)	13,809,000		13,226,000
Non-current (Pension and severance obligations)	133,701,000		133,435,000
Total Korean severance obligation	$ 147,510,000		$ 146,661,000
Minimum [Member] | Korean Severance Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued severance plan, minimum service period	1 year