Note 12 - Fair Value - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Mortgage-backed securities, at fair value (includes pledged assets of $6,506,372 and $3,719,906, respectively)	$ 3,540,002	$ 6,511,095
U.S. Treasury Notes, at fair value (includes pledged assets of $29,740 and $0, respectively)	36,382	37,175
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $6,506,372 and $3,719,906, respectively)	0	0
U.S. Treasury Notes, at fair value (includes pledged assets of $29,740 and $0, respectively)	36,382	36,382
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Interest Rate Swap [Member]
Derivative assets, at fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Payer Swaptions [Member]
Derivative assets, at fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Interest Rate Cap [Member]
Derivative assets, at fair value	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | TBA Contracts [Member]
Derivative assets, at fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $6,506,372 and $3,719,906, respectively)	3,540,002	6,511,095
U.S. Treasury Notes, at fair value (includes pledged assets of $29,740 and $0, respectively)	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Interest Rate Swap [Member]
Derivative assets, at fair value	4,983	26,431
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Payer Swaptions [Member]
Derivative assets, at fair value	27,416	17,070
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Interest Rate Cap [Member]
Derivative assets, at fair value	1,119
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | TBA Contracts [Member]
Derivative assets, at fair value	(507)	(304)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $6,506,372 and $3,719,906, respectively)	0	0
U.S. Treasury Notes, at fair value (includes pledged assets of $29,740 and $0, respectively)	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Interest Rate Swap [Member]
Derivative assets, at fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Payer Swaptions [Member]
Derivative assets, at fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Interest Rate Cap [Member]
Derivative assets, at fair value	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | TBA Contracts [Member]
Derivative assets, at fair value	$ 0	$ 0