Supplemental Financial Data - Oil and Gas Producing Activities (unaudited) (Details Textual)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Supplemental Financial Data - Oil and Gas Producing Activities (unaudited) (Textual)
Estimated proved reserves, description	3.0 Bcfe	3.0 Bcfe
Discount rate, description	All cash flow amounts, including income taxes, are discounted at 10%.
Carbon California [Member]
Supplemental Financial Data - Oil and Gas Producing Activities (unaudited) (Textual)
Propotionate share, percentage		17.81%
Carbon Appalachia [Member]
Supplemental Financial Data - Oil and Gas Producing Activities (unaudited) (Textual)
Propotionate share, percentage		27.24%
Purchases of reserves-in-place, description	We held a 2.98%, 16.04%, 19.37%, and 27.24% proportionate share of Carbon Appalachia for the period April 3, 2017 through August 14, 2017; August 15, 2017 through September 28, 2017; September 29, 2017 through October 31, 2017; November 1, 2017 through December 31, 2017, respectively.