Annual report pursuant to Section 13 and 15(d)

Supplemental Oil and Gas Disclosures - Standardized Measure of Discounted Future Net Cash Flows (Parenthetical) (Details)

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Supplemental Oil and Gas Disclosures - Standardized Measure of Discounted Future Net Cash Flows (Parenthetical) (Details) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Extractive Industries [Abstract]      
Income taxes $ (74,800,000) [1] $ 0 $ 0
[1] No future income taxes were estimated for 2016 and 2015 as our tax position had sufficient tax basis to offset estimated future taxes. State income taxes were disregarded due to immateriality.