Note 6 - Pledged Assets - Schedule of Financial Instruments Owned and Pledged as Collateral (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Accrued interest receivable	$ 53,411	$ 49,127
Restricted cash	131,037	58,696
Asset Pledged as Collateral [Member]
Accrued interest receivable	52,994	48,573
Restricted cash	131,037	58,696
Total	11,813,664	10,745,145
Asset Pledged as Collateral [Member] \| Residential Mortgage-Backed Securities [Member] \| Pass Through Certificate [Member]
Investment at fair value	11,434,805	10,489,655
Asset Pledged as Collateral [Member] \| Residential Mortgage-Backed Securities [Member] \| Structured Finance [Member]
Investment at fair value	11,966	13,088
Asset Pledged as Collateral [Member] \| US Treasury Securities [Member]
Investment at fair value	182,862	135,133
Asset Pledged as Collateral [Member] \| Repurchase Agreements [Member]
Accrued interest receivable	52,394	48,537
Restricted cash	111,469	51,171
Total	11,610,634	10,602,451
Asset Pledged as Collateral [Member] \| Repurchase Agreements [Member] \| Residential Mortgage-Backed Securities [Member] \| Pass Through Certificate [Member]
Investment at fair value	11,434,805	10,489,655
Asset Pledged as Collateral [Member] \| Repurchase Agreements [Member] \| Residential Mortgage-Backed Securities [Member] \| Structured Finance [Member]
Investment at fair value	11,966	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	600	36
Restricted cash	19,568	7,525
Total	203,030	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	$ 182,862	$ 135,133