Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Inventory cost	$ 15,154	$ 10,423
Accrued expenses and accounts receivable	5,294	4,420
Foreign tax credits		5,848
Research and development tax credits	15,807	16,263
Net operating loss carryforwards	42,734	24,139
Lease obligations	2,982	3,773
Plant, equipment and intangible assets	162
Accrued pension	6,386	4,629
Share based compensation and others	8,810	7,805
Total deferred tax assets, include valuation allowance	97,329	77,300
Valuation allowances	(45,591)	(29,414)
Total deferred tax assets, non-current	51,738	47,886
Deferred tax liabilities
Plant, equipment and intangible assets		(13,816)
Right of use assets	(2,936)	(4,008)
Outside basis differences and others	(13,467)	(23,648)
Total deferred tax liabilities, non-current	(16,403)	(41,472)
Net deferred tax assets	$ 35,335	$ 6,414