Leases - Balance Sheet Location (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Operating leases
Operating lease right-of-use assets	$ 14,403	$ 16,069
Other accrued liabilities	2,444	2,553
Long-term operating lease liabilities	11,959	13,516
Total operating lease liabilities	14,403	16,069
Finance leases
Property, plant, and equipment	1,162	1,116
Accumulated amortization	(977)	(869)
Property, plant, and equipment - net	185	247
Current maturities of long-term debt	111	119
Long-term debt	74	128
Total finance lease liabilities	$ 185	$ 247
Operating lease, liability, current, statement of financial position	Other accrued liabilities	Other accrued liabilities
Finance lease, right-of-use asset, statement of financial position	Property, plant, and equipment - net (Note 8)	Property, plant, and equipment - net (Note 8)
Finance lease, liability, current, statement of financial position	Long-term Debt and Lease Obligation, Current	Long-term Debt and Lease Obligation, Current
Finance lease, liability, noncurrent, statement of financial position	Long-term portion	Long-term portion