Significant Accounting Policies (Details Textuals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Accounting Policies [Line Items]
Loans and Leases Receivable, Net Amount	$ 17,000
Ceiling test write-down	0	$ 810,921	$ 4,939,600
Impairments of unevaluated costs	21,400	21,000	17,900
CO2 pipelines not placed in service	101,100
Impairment of goodwill	0	0	$ 1,261,512
Amortization of Intangible Assets	$ 2,400	$ 2,300
Minimum | Pipelines
Significant Accounting Policies [Line Items]
Estimated useful lives	15 years
Minimum | Vehicles
Significant Accounting Policies [Line Items]
Estimated useful lives	5 years
Minimum | Furniture and Fixtures
Significant Accounting Policies [Line Items]
Estimated useful lives	5 years
Minimum | Computer equipment and software
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Maximum | Pipelines
Significant Accounting Policies [Line Items]
Estimated useful lives	50 years
Maximum | Vehicles
Significant Accounting Policies [Line Items]
Estimated useful lives	10 years
Maximum | Furniture and Fixtures
Significant Accounting Policies [Line Items]
Estimated useful lives	10 years
Maximum | Computer equipment and software
Significant Accounting Policies [Line Items]
Estimated useful lives	5 years