Commitments and Contingencies (Commitments) (Details Textuals) $ in Millions		12 Months Ended
	Dec. 31, 2019 MMcf / d $ / Barrel MMcf	Dec. 31, 2019 USD ($) MMcf / d MMcf
Industrial-source CO2
Long-term Purchase Commitment [Line Items]
Term of long-term purchase commitments		9 years
Oil price assumption for obligation estimate ($/Bbl) | $ / Barrel	60
Industrial-source CO2 | Minimum
Long-term Purchase Commitment [Line Items]
Aggregate purchase obligation of CO2		$ 14.0
Industrial-source CO2 | Maximum
Long-term Purchase Commitment [Line Items]
Aggregate purchase obligation of CO2		$ 33.0
CO2 Volumetric Production Payments and Industrial CO2 Customers
Long-term Purchase Commitment [Line Items]
Significant supply commitment remaining volume committed (MMcf) | MMcf	770,000	770,000
Term of long-term supply arrangement		15 years
Significant supply commitment yearly maximum volume required (MMcf/d) | MMcf / d	257	257
Helium Supply Arrangement
Long-term Purchase Commitment [Line Items]
Term of long-term supply arrangement		20 years
Maximum payment in event of shortfall		$ 46.0