Note 6 - Pledged Assets - Schedule of Financial Instruments Owned and Pledged as Collateral (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Accrued interest receivable	$ 39,353	$ 23,044
Restricted cash	33,321	25,723
Asset Pledged as Collateral [Member]
Accrued interest receivable	39,200	22,852
Restricted cash	33,321	25,723
Total	8,517,899	5,358,194
Asset Pledged as Collateral [Member] | Residential Mortgage-Backed Securities [Member] | Pass Through Certificate [Member]
Investment at fair value	8,305,758	5,193,570
Asset Pledged as Collateral [Member] | Residential Mortgage-Backed Securities [Member] | Structured Finance [Member]
Investment at fair value	14,180	15,498
Asset Pledged as Collateral [Member] | US Treasury Securities [Member]
Investment at fair value	125,440	100,551
Asset Pledged as Collateral [Member] | Repurchase Agreements [Member]
Accrued interest receivable	38,031	22,852
Restricted cash	26,357	22,818
Total	8,384,326	5,254,738
Asset Pledged as Collateral [Member] | Repurchase Agreements [Member] | Residential Mortgage-Backed Securities [Member] | Pass Through Certificate [Member]
Investment at fair value	8,305,758	5,193,570
Asset Pledged as Collateral [Member] | Repurchase Agreements [Member] | Residential Mortgage-Backed Securities [Member] | Structured Finance [Member]
Investment at fair value	14,180	15,498
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	1,169	0
Restricted cash	6,964	2,905
Total	133,573	103,456
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	$ 125,440	$ 100,551