Note 5 - Derivative and Other Hedging Instruments (Details Textual) $ in Thousands	Jun. 30, 2024 USD ($) $ / item	Dec. 31, 2023 USD ($) $ / item
Dual Digital Option, Covenant, S&P 500 Index	4,725.166
Dual Digital Option, Covenant, SOFR 10 Year Swap Rate	3.883%
Dual Digital Option, Amount, Covenants Not Met	$ 0
Five Year Treasury Note Futures [Member] | Short [Member]
Derivative, Forward Price (in USD per Per Share) | $ / item	106.58	108.77
Derivative, Fair Value, Net	$ 449,200	$ 458,500
Ten Year Ultra Future [Member] | Short [Member]
Derivative, Forward Price (in USD per Per Share) | $ / item		112.89
Derivative, Fair Value, Net	$ 361,200	$ 361,200