Leases (Financing Leases) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2013	Sep. 30, 2019	Aug. 31, 2019
Lessee, Lease, Description [Line Items]
Financing lease obligations	$ 1,653
Weighted-average discount rate - finance leases	6.67%
Minimum lease payment	$ 1,872
CO2 Compressor
Lessee, Lease, Description [Line Items]
Financing lease obligations		$ 24,500	$ 9,832	$ 9,832
Finance lease, term		84 months
Option to purchase for a specified price, period		72 months
Weighted-average discount rate - finance leases		3.80%
Minimum lease payment		$ 3,181
Fleet Trucks
Lessee, Lease, Description [Line Items]
Finance lease, term	48 months
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 1,911