Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Oil and gas revenue receivable and other receivables, net of allowances	$ 10,427	$ 8,350
Common stock, No par value
Common stock, Shares authorized	Unlimited	Unlimited
Common stock, Shares issued	197,840,056	197,383,295
Common stock, Shares outstanding	197,840,056	197,383,295

For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.

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Face amount per share of no-par value common stock.

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Indicates that the number of common shares permitted to be issued by an entity's charter and bylaws is unlimited. The acceptable value is "Unlimited".

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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