Note 6 - Revenue 2 (Details Textual) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 $ in Millions |
Jun. 30, 2023
USD ($)
|
|---|---|
| Fixed-Price Contract [Member] | |
| Revenue, Remaining Performance Obligation, Amount | $ 470 |
| Revenue, Remaining Performance Obligation, Percentage | 49.00% |
| Contracts with Price Reopeners [Member] | |
| Revenue, Remaining Performance Obligation, Amount | $ 122 |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Year) | 1 year |
| Energy Obligations [Member] | |
| Revenue, Remaining Performance Obligation, Amount | $ 139 |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Year) | 2 years |
| Contract Capacity [Member] | |
| Revenue, Remaining Performance Obligation, Amount | $ 83 |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Year) | 2025 years |