Note 6 - Income Taxes (Details Textual) - State and Local Jurisdiction [Member] - USD ($) $ in Millions |
3 Months Ended | |||
|---|---|---|---|---|
Sep. 30, 2023 |
Jun. 30, 2023 |
Sep. 30, 2022 |
Jun. 30, 2022 |
|
| Iowa, Kansas, and Arkansas [Member] | ||||
| Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability | $ (41) | |||
| Iowa, Arkansas, and Idaho Department of Revenue [Member] | ||||
| Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability | $ (40) | |||
| Nebraska Department of Revenue [Member] | ||||
| Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability | $ (73) | $ (55) | ||