Note 5 - Derivative and Other Hedging Instruments (Details Textual) - Short [Member] $ / item in Thousands, $ in Thousands |
Sep. 30, 2026
USD ($)
$ / item
|
Dec. 31, 2025
USD ($)
$ / item
|
|---|---|---|
| Ten Year T-Note Futures [Member] | ||
| Derivative, Forward Price (in USD per Per Share) | $ / item | 104,200 | 112,440 |
| Derivative, Fair Value, Net | $ | $ 894,700 | $ 101,200 |
| Ten Year Ultra Futures [Member] | ||
| Derivative, Forward Price (in USD per Per Share) | $ / item | 105,000 | 115,020 |
| Derivative, Fair Value, Net | $ | $ 588,000 | $ 69,000 |
| Thirty Year Treasury Note Futures [Member] | ||
| Derivative, Forward Price (in USD per Per Share) | $ / item | 155,400 | |
| Derivative, Fair Value, Net | $ | $ 103,590 | |
| Five Year Treasury Note Futures [Member] | ||
| Derivative, Forward Price (in USD per Per Share) | $ / item | 133,900 | |
| Derivative, Fair Value, Net | $ | $ 109,300 |