Basis of Presentation - Narrative (Details) - shares	Sep. 30, 2025	Jan. 14, 2025
Basis of Presentation [Line Items]
Preferred stock, shares authorized (in shares)	500,000
Preferred stock, shares issued (in shares)	0
Preferred stock, shares outstanding (in shares)	0
Arch Resources, Inc
Basis of Presentation [Line Items]
Business acquisition, percentage	35.00%	45.00%

Basis of Presentation

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- Definition

Percentage of voting equity interest acquired in business combination.

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-Section 50
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- Definition

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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- Definition

Number of shares issued for nonredeemable preferred shares and preferred shares redeemable solely at option of issuer. Includes, but is not limited to, preferred shares issued, repurchased, and held as treasury shares. Excludes preferred shares classified as debt.

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- Definition

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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