Debt Long Term Debt (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term and short-term debt	$ 1,578,000	$ 1,545,000
Less: Short-term borrowings and current portion of long-term debt	0	0
Long-term debt (including related party)	1,578,000	1,545,000
Senior Notes Due May 2018 [Member]
Debt Instrument [Line Items]
Senior notes	345,000	345,000
Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Senior notes	400,000	400,000
Senior Notes Due October 2022 [Member]
Debt Instrument [Line Items]
Senior notes	300,000	300,000
Convertible Senior Subordinated Notes Due April 2014 [Member]
Debt Instrument [Line Items]
Convertible subordinated notes	250,000	250,000
Term Loan Due March 2015 [Member] | Korea Subsidiaries [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percentage)	2.30%
Term Loan for subsidiaries	100,000	100,000
Term Loan Due July 2017 [Member] | Korea Subsidiaries [Member]
Debt Instrument [Line Items]
Term Loan for subsidiaries	150,000	137,000
Term Loan Due September 2017 [Member] | Korea Subsidiaries [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percentage)	1.75%
Term Loan for subsidiaries	10,000	0
Term Loan Due December 2019 [Member] | Korea Subsidiaries [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percentage)	3.70%
Term Loan for subsidiaries	23,000	13,000
Revolving Credit Facility Due April 2015 [Member] | Taiwan Subsidiaries [Member]
Debt Instrument [Line Items]
Borrowing under senior secured credit facility	0	0
Revolving Credit Facility 2.33% due June 2013 [Member] | Korea Subsidiaries [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percentage)	2.33%
Borrowing under senior secured credit facility	0	0
$150 million revolving credit facility, LIBOR plus 1.5%-2.25%, due June 2017 [Member]
Debt Instrument [Line Items]
Borrowing under senior secured credit facility	$ 0	$ 0