Income Taxes Deferred Tax Assets Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carry-forwards	$ 10,622	$ 13,892
Tax credit carry-forwards	4,658	2,996
Accruals for compensation	7,440	8,587
Accruals for inventory capitalization	3,192	3,445
Unrealized benefit from corporate restructuring	49,313	53,501
Intangibles	582	830
Unrealized benefit plan loss	1,974	2,366
Unrealized foreign exchange	2,853	2,852
UK tax rate change	905	0	$ 0
Unearned revenue	1,024	741
Other	3,860	1,989
Total deferred tax assets	86,423	91,199
Valuation allowance	(7,377)	(6,264)
Net deferred tax assets	79,046	84,935
Deferred tax liabilities:
Property, plant and equipment	(4,139)	(4,998)
Accrued withholding taxes	(27,544)	(26,916)
Unrealized foreign exchange	(1,070)	(610)
Other	(167)	(221)
Total deferred tax liabilities	(32,920)	(32,745)
Net deferred income taxes	46,126	52,190
Long-term deferred tax assets	70,462	72,775
Long-term deferred tax liabilities	(24,336)	(20,585)
Total deferred tax assets (liabilities)	$ 46,126	$ 52,190