Summary of Significant Accounting Policies - Summary of Unaudited Pro Forma Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Total oil and gas sales	$ 126,881
Net income (loss)	$ 13,575
Net income (loss) per share – basic and diluted	$ 0.13
Pro Forma
Total oil and gas sales		$ 132,553
Net income (loss)		$ (6,231)
Net income (loss) per share – basic and diluted		$ (0.06)

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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