Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Significant components of deferred tax assets and liabilities
Post-retirement benefits	$ 947	$ 1,226
Inventory reserves	251	69
Loss carry-forwards	4,547	5,070
Credit carry-forwards	10,467	19,665
Accrued expenses	4,543	4,917
Research and development expenditures	19,448	19,226
Operating lease liabilities	5,865	5,643
Stock compensation	2,426	1,970
Foreign exchange loss	2,075	2,052
Other	835	769
Gross deferred tax assets	51,404	60,607
Depreciation and amortization	23,067	13,386
Pensions	0	10,958
Qualified replacement plan	3,507	0
Operating lease assets	5,531	5,307
Subsidiaries' unremitted earnings	2,562	1,947
Other	900	0
Gross deferred tax liabilities	35,567	31,598
Net deferred tax assets	15,837	29,009
Deferred tax asset valuation allowance	(8,386)	(9,489)
Total net deferred tax assets	$ 7,451	$ 19,520