Leases - Supplemental Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Jan. 01, 2019
Operating leases:
Operating lease right-of-use assets	$ 3,164	$ 3,255
Current operating lease liabilities	1,199	1,126
Long-term lease obligations	2,333	2,482
Operating Lease, Liability	3,532	3,608	$ 78,400
Finance leases:
Properties, plants and equipment	6,554	6,968
Accumulated amortization	(3,354)	(4,547)
Properties, plants and equipment, net	3,200	2,421
Current finance lease liabilities	3,459	3,224
Noncurrent finance lease liabilities	69,180	70,475
Total finance lease liabilities	$ 72,639	$ 73,699
Weighted average remaining lease term (in years)
Operating leases	6 years	6 years 6 months
Finance leases	16 years 2 months 12 days	17 years
Weighted average discount rate
Operating leases	4.80%	5.00%
Finance leases	5.60%	6.00%