Debt Long Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	$ 1,639,938	$ 1,590,655
Less: Unamortized premium and deferred debt costs, net	(3,219)	(3,616)
Less: Short-term borrowings and current portion of long-term debt	(96,215)	(76,770)
Long-term debt (including related party)	1,540,504	1,510,269
$200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 (1) | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	100,000	100,000
6.625% Senior notes, due June 2021, $75 million related party | Senior notes (Level 1)
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	400,000	400,000
6.375% Senior notes, due October 2022 | Senior notes (Level 1)
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	524,971	525,000
KOREA, REPUBLIC OF | $100 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due June 2017 (2) | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	55,000	40,000
KOREA, REPUBLIC OF | Term loan, LIBOR plus 2.60%, due May 2018 | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	120,000	120,000
KOREA, REPUBLIC OF | Term loan, LIBOR plus 2.70%, due December 2019 | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	70,000	70,000
KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.35%, due May 2020 | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	150,000	150,000
KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.35%, due May 2020 | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	80,000	80,000
KOREA, REPUBLIC OF | Term loan, fund floating rate plus 1.60%, due June 2020 (3) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	64,000	40,000
JAPAN | Short-term term loans, variable rate (4) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	25,267	15,582
JAPAN | Short-term term loans, fixed rate at 0.50% | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	0	5,808
JAPAN | Term loans, TIBOR plus 1.00%, due November 2016 | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	1,215	2,800
JAPAN | Term loans, fixed rate at 0.53%, due April 2018 | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	29,485	31,465
TAIWAN, PROVINCE OF CHINA | Revolving credit facility, TAIFX plus a bank-determined spread, due November 2020 (5) | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	$ 20,000	$ 10,000