Leases - Supplemental Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating leases:
Operating lease right-of-use assets	$ 3,454		$ 0
Current operating lease liabilities	807		0
Long-term lease obligations	2,995		0
Total operating lease liabilities	3,802	$ 78,400
Finance leases:
Properties, plants and equipment	6,741
Accumulated amortization	(4,858)
Properties, plants and equipment, net	1,883
Current finance lease liabilities	5,426		936
Noncurrent finance lease liabilities	69,168		$ 867
Total finance lease liabilities	$ 74,594
Weighted average remaining lease term (in years)
Operating leases	6 years 7 months 6 days
Finance leases	17 years 4 months 24 days
Weighted average discount rate
Operating leases	5.00%
Finance leases	6.00%