Commitments and Contingencies Commitments and Contingencies - Narrative - Other Matters, Claims and Legal Proceedings (Details) $ in Millions	6 Months Ended
Jun. 30, 2020 USD ($)
Loss Contingencies [Line Items]
Montana Department of Revenue tax refund judgment	$ 4.8
Cascade County refund settlement	1.2
Montana Department of Revenue total refund judgment received	$ 6.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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