Income Taxes Deferred Tax Assets Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carry-forwards	$ 13,892	$ 7,209
Tax credit carry-forwards	2,996	1,888
Accruals for compensation	8,587	8,240
Accruals for inventory capitalization	3,445	1,788
Unrealized benefit from corporate restructuring	53,501	56,985
Intangibles	830
Unrealized benefit plan loss	2,366	3,740
Unrealized foreign exchange	2,852	3,842
Unearned revenue	741	1,849
Other	1,989	1,839
Total deferred tax assets	91,199	87,380
Valuation allowance	(6,264)	(6,241)
Net deferred tax assets	84,935	81,139
Deferred tax liabilities:
Intangibles		(6,263)
Property, plant and equipment	(4,998)	(3,546)
Accrued interest		(1,679)
Accrued withholding taxes	(26,916)	(26,718)
Unrealized foreign exchange	(610)	(2,653)
Other	(221)	(306)
Total deferred tax liabilities	(32,745)	(41,165)
Net deferred income taxes	52,190	39,974
Long-term deferred tax assets	72,775	67,312
Long-term deferred tax liabilities	(20,585)	(27,338)
Total deferred tax assets (liabilities)	$ 52,190	$ 39,974