Debt (Long Term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Aug. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt	$ 1,334,129		$ 1,365,533
Less: Unamortized premium and deferred debt costs, net	(1,818)		(1,104)
Less: Short-term borrowings and current portion of long-term debt	(114,579)		(123,848)
Long-term debt	1,217,732		1,240,581
6.625% Senior notes, due June 2021 | Senior notes
Debt Instrument [Line Items]
Total debt	0	$ 200,000
6.375% Senior notes, due October 2022 | Senior notes
Debt Instrument [Line Items]
Total debt	524,971		524,971
$250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Total debt	0		0
Korea | $75 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due September 2018 | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Total debt	0		75,000
Korea | $30 million revolving credit facility, LIBOR plus the applicable bank rate, due October 2019 | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Total debt	0		0
Korea | Term loan, LIBOR plus 2.70%, due December 2019 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	0		55,000
Korea | Term loan, foreign currency funding-linked base rate plus 1.32%, due May 2020 (2) | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	0		150,000
Korea | Term loan, fixed rate at 3.70%, due May 2020 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	120,000		120,000
Korea | Term loan, fund floating rate plus 1.60%, due June 2020 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	125,000		86,000
Korea | Term loan, LIBOR plus 2.56%, due December 2023 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	200,000		0
Korea | Term loan, applicable bank rate plus 1.98%, due December 2028 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	24,000		0
Japan | Short-term term loans, variable rates | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	8,232		30,455
Japan | Term loans, fixed rate at 0.53%, due April 2018 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	0		6,744
Japan | Term loan, fixed rate at 0.86%, due June 2022 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	31,908		39,933
Japan | Term loan, fixed rate at 0.60%, due July 2022 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	6,838		8,430
Japan | Term loan, fixed rate at 1.30%, due July 2023 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	225,180		0
Taiwan | Revolving credit facility, TAIFX plus a bank-determined spread, due November 2020 (Taiwan) | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Total debt	20,000		20,000
China | Term loan, LIBOR plus 1.80% due December 2019
Debt Instrument [Line Items]
Total debt	$ 48,000		$ 49,000