Note 6 - Pledged Assets - Schedule of Financial Instruments Owned and Pledged as Collateral (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Accrued interest receivable	$ 53,076	$ 49,127
Restricted cash	151,545	58,696
Asset Pledged as Collateral [Member]
Accrued interest receivable	52,825	48,573
Restricted cash	151,545	58,696
Total	11,026,011	10,745,145
Asset Pledged as Collateral [Member] \| Residential Mortgage-Backed Securities [Member] \| Pass Through Certificate [Member]
Investment at fair value	10,602,397	10,489,655
Asset Pledged as Collateral [Member] \| Residential Mortgage-Backed Securities [Member] \| Structured Finance [Member]
Investment at fair value	11,383	13,088
Asset Pledged as Collateral [Member] \| US Treasury Securities [Member]
Investment at fair value	207,861	135,133
Asset Pledged as Collateral [Member] \| Repurchase Agreements [Member]
Accrued interest receivable	51,085	48,537
Restricted cash	130,044	51,171
Total	10,794,909	10,602,451
Asset Pledged as Collateral [Member] \| Repurchase Agreements [Member] \| Residential Mortgage-Backed Securities [Member] \| Pass Through Certificate [Member]
Investment at fair value	10,602,397	10,489,655
Asset Pledged as Collateral [Member] \| Repurchase Agreements [Member] \| Residential Mortgage-Backed Securities [Member] \| Structured Finance [Member]
Investment at fair value	11,383	13,088
Asset Pledged as Collateral [Member] \| Repurchase Agreements [Member] \| US Treasury Securities [Member]
Investment at fair value	0	0
Asset Pledged as Collateral [Member] \| Derivative [Member]
Accrued interest receivable	1,740	36
Restricted cash	21,501	7,525
Total	231,102	142,694
Asset Pledged as Collateral [Member] \| Derivative [Member] \| Residential Mortgage-Backed Securities [Member] \| Pass Through Certificate [Member]
Investment at fair value	0	0
Asset Pledged as Collateral [Member] \| Derivative [Member] \| Residential Mortgage-Backed Securities [Member] \| Structured Finance [Member]
Investment at fair value	0	0
Asset Pledged as Collateral [Member] \| Derivative [Member] \| US Treasury Securities [Member]
Investment at fair value	$ 207,861	$ 135,133