Business Segments (Textual) (Details)	12 Months Ended
Dec. 31, 2021
Coal Mining customer \| Customer concentration risk \| Earnings of Unconsolidated Mines \| Top Two Customers - Basin Electric and GRE
Segment Reporting Information [Line Items]
Revenue from major customer, percentage	68.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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