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Restricted Certificate of Deposit	6 Months Ended
Restricted Certificate of Deposit	Jun. 30, 2017
Certificates Of Deposit [Abstract]
Restricted Certificate of Deposit	4. Restricted Certificate of Deposit The Company is required to maintain a certificate of deposit (“CD”) issued by a municipality in Montana, in which certain of our drilling operations are located. This CD is pledged as collateral for a letter of credit issued by the Company’s bank to the municipality. The CD has a maturity date of March 8, 2018, and bears an interest rate of 0.25%. As this CD is expected to be renewed upon maturity and is not available for use in operations, it is classified as a noncurrent asset.