Debt (Long Term Debt) (Details) $ in Thousands, ₩ in Billions, ¥ in Billions	1 Months Ended				12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2020 JPY (¥)	Apr. 30, 2020 USD ($)	Apr. 30, 2020 KRW (₩)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 KRW (₩)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2020 KRW (₩)	May 31, 2020 KRW (₩)	Jul. 31, 2019 USD ($)
Debt Instrument [Line Items]
Total debt	$ 1,164,302				$ 1,164,302		$ 1,460,351
Less: Unamortized discount and deferred debt costs, net	(9,956)				(9,956)		(10,117)
Less: Short-term borrowings and current portion of long-term debt	(149,007)				(149,007)		(144,479)
Long-term debt	1,005,339				1,005,339		1,305,755
Proceeds from revolving credit facilities					312,000		272,700	$ 0
Payments of revolving credit facilities					332,000		272,700	75,000
Proceeds from issuance of long-term debt	105,000
6.625% Senior notes, due September 2027 | Senior notes
Debt Instrument [Line Items]
Total debt	$ 525,000				$ 525,000		525,000
Interest rate (as a percent)	6.625%				6.625%				6.625%
Other
Debt Instrument [Line Items]
Total debt	$ 2,039				$ 2,039		0
$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		0
Credit facility, borrowing capacity	250,000				250,000
Proceeds from revolving credit facilities					150,000
Payments of revolving credit facilities					150,000
Remaining borrowing capacity	250,000				250,000
Korea | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Credit facility, borrowing capacity	30,000				30,000
Proceeds from revolving credit facilities					60,000
Payments of revolving credit facilities					60,000
Amount of unused borrowing capacity	$ 30,000				$ 30,000
Korea | Revolving Credit Facility due October 2021 | Line of Credit | Applicable Bank Rate
Debt Instrument [Line Items]
Interest rate (as a percent)	1.11%				1.11%				1.11%
Korea | Revolving Credit Facility due October 2021 | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Total debt	$ 0				$ 0
Korea | Revolfing Credit Facility, due October 2020 | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Total debt							0
Korea | Term loan, fund floating rate plus 1.60%, due June 2020 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	0				$ 0		$ 24,000
Interest rate (as a percent)							3.90%
Korea | Term loan, fund floating rate plus 1.60%, due June 2020 | Subsidiary Term Loans | Fund Floating Rate
Debt Instrument [Line Items]
Interest rate spread (as a percent)					1.60%	1.60%
Korea | Fixed Rate Term Loan Due May 2021 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	$ 0				$ 0		$ 0
Interest rate (as a percent)	1.80%				1.80%				1.80%
Korea | Term loan, applicable bank rate plus 2.03%, due July 2022 | Subsidiary Term Loans | Applicable Bank Rate
Debt Instrument [Line Items]
Total debt	$ 0				$ 0		40,000
Interest rate spread (as a percent)					2.03%	2.03%
Korea | Term loan, applicable bank rate plus 2.03%, due September 2022 (3) | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	0				$ 0		60,000
Amount of debt agreement											$ 140,000
Proceeds from issuance of long-term debt					80,000
Repayments of debt					$ 140,000
Korea | Term loan, applicable bank rate plus 2.03%, due September 2022 (3) | Subsidiary Term Loans | Applicable Bank Rate
Debt Instrument [Line Items]
Interest rate spread (as a percent)					2.03%	2.03%
Korea | Term loan, applicable bank rate plus 1.77%, April 2023 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	51,541				$ 51,541		0
Proceeds from issuance of long-term debt			$ 122,000	₩ 150
Repayments of debt					$ 86,000	₩ 94
Korea | Term loan, applicable bank rate plus 1.77%, April 2023 | Subsidiary Term Loans | Applicable Bank Rate
Debt Instrument [Line Items]
Interest rate spread (as a percent)					1.77%	1.77%
Korea | Term loan, LIBOR plus 2.56%, due December 2023 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	0				$ 0		200,000
Korea | Term loan, LIBOR plus 2.56%, due December 2023 | Subsidiary Term Loans | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)					2.56%	2.56%
Korea | Term loan, applicable bank rate plus 1.98%, due December 2028 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	$ 50,000				$ 50,000		66,000
Amount of debt agreement								$ 90,000
Weighted average interest rate	3.88%				3.88%				3.88%
Korea | Term loan, applicable bank rate plus 1.98%, due December 2028 | Subsidiary Term Loans | Applicable Bank Rate
Debt Instrument [Line Items]
Interest rate spread (as a percent)					1.98%	1.98%
Korea | Term loan due May 2021 | Subsidiary Term Loans
Debt Instrument [Line Items]
Amount of unused borrowing capacity	$ 55,000				$ 55,000				₩ 60
Amount of debt agreement | ₩										₩ 60
Proceeds from issuance of long-term debt					48,400	₩ 60
Repayments of debt					48,400	₩ 60
Japan | Short-term term loans, variable rates | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	6,663				6,663		7,071
Amount of unused borrowing capacity	4,800				4,800
Japan | Term loan, fixed rate at 0.86%, due June 2022 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	$ 14,528				$ 14,528		23,018
Interest rate (as a percent)	0.86%				0.86%				0.86%
Japan | Term loan, fixed rate at 0.60%, due July 2022 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	$ 3,390				$ 3,390		5,064
Interest rate (as a percent)	0.60%				0.60%				0.60%
Japan | Term loan, fixed rate at 1.30%, due July 2023 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	$ 138,499				$ 138,499		179,541
Interest rate (as a percent)	1.30%				1.30%				1.30%
Japan | Term loan, fixed rate at 1.35%, due December 2024 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	$ 220,823				$ 220,823		262,407
Interest rate (as a percent)	1.35%				1.35%				1.35%
Japan | Term Loan, Fixed Rate at 1.20% Due December 2025 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	$ 105,569				$ 105,569		0
Interest rate (as a percent)	1.20%				1.20%				1.20%
Proceeds from issuance of long-term debt | ¥		¥ 10.9
China | Term loan, LIBOR plus 1.60%, due March 2022 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	$ 28,000				$ 28,000		29,000
China | Term loan, LIBOR plus 1.60%, due March 2022 | Subsidiary Term Loans | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)					1.60%	1.60%
China | Term loan, LIBOR Plus 1.40%, due March 2022 | Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	18,250				$ 18,250		19,250
China | Term loan, LIBOR Plus 1.40%, due March 2022 | Subsidiary Term Loans | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)					1.40%	1.40%
Taiwan | Credit facility, TAIFX plus the applicable bank rate, due December 2024 | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Total debt	0				$ 0		20,000
Credit facility, borrowing capacity							36,000
Proceeds from revolving credit facilities					72,000
Payments of revolving credit facilities					92,000
Amount of unused borrowing capacity	$ 36,000				$ 36,000
Amount of debt agreement							20,000
Long-term debt							$ 56,000
Minimum | $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility | Line of Credit | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)					1.25%	1.25%
Maximum | $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility | Line of Credit | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)					1.75%	1.75%