Leases - Balance Sheet Location (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Operating leases
Operating lease right of use assets	$ 15,010	$ 16,069
Other accrued liabilities	2,528	2,553
Long-term operating lease liabilities	12,482	13,516
Total operating lease liabilities	15,010	16,069
Finance leases
Property, plant, and equipment	1,163	1,116
Accumulated amortization	(943)	(869)
Property, plant, and equipment - net	220	247
Current maturities of long-term debt	124	119
Long-term debt	96	128
Total finance lease liabilities	$ 220	$ 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	us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent	us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent
Finance lease, liability, noncurrent, statement of financial position	Long-term portion	Long-term portion