Summary of Significant Accounting Policies, Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Property and Equipment [Abstract]
Oil and gas property impairment	$ 3	$ 29
Minimum [Member]
Property and Equipment [Abstract]
Property and equipment, useful life	3 years
Maximum [Member]
Property and Equipment [Abstract]
Property and equipment, useful life	20 years
Producing Property Impairments [Member]
Property and Equipment [Abstract]
Oil and gas property impairment	$ 0	1
Non-Producing Property Impairments [Member]
Property and Equipment [Abstract]
Oil and gas property impairment	$ 3	$ 28
Onshore Leasehold [Member]
Property and Equipment [Abstract]
Onshore normal leasehold period	3 years