Income Taxes - Schedule of Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Accrued expenses	$ 620	$ 558
Allowance for doubtful accounts	269	371
Contract overrun reserves	680	546
Deferred compensation	272	113
Deferred revenue	1,570	18
Employment-related accruals	4,028	5,912
Environmental reserves	499	493
Federal tax credit carryforwards	133	133
Inventory reserves	2,957	2,684
Operating lease liabilities	8,145	4,186
Pension obligation	1,550	2,915
Federal and state net operating loss carryforwards	4,243	5,125
State tax credit carryforwards	7,123	9,271
Stock-based compensation	2,584	2,179
Other	2,503	1,526
Total gross deferred tax assets	37,176	36,030
Valuation allowance	(7,718)	(9,330)
Total gross deferred tax assets, net of valuation allowance	29,458	26,700
Deferred tax liabilities:
Depreciation	(11,986)	(11,255)
Goodwill	(6,557)	(5,493)
Intangibles	(20,337)	(22,298)
Operating lease right-of-use assets	(7,931)	(3,879)
Prepaid insurance	(534)	(385)
Other	(840)	(349)
Total gross deferred tax liabilities	(48,185)	(43,659)
Net deferred tax liabilities	$ (18,727)	$ (16,959)