Note 13 - Fair Value - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Mortgage-backed securities, at fair value (includes pledged assets of $4,521,136 and $3,885,554, respectively)	$ 4,525,755	$ 3,894,012
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] | Dual Digital Option [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 1 [Member] | Fair Value, Recurring [Member] | Payer Swaptions [Member]
Derivative assets, at fair value		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $4,521,136 and $3,885,554, respectively)	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $4,521,136 and $3,885,554, respectively)	98,099
Derivative asset, fair value		148,820
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Interest Rate Swap [Member]
Derivative assets, at fair value	29,214	6,348
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Dual Digital Option [Member]
Derivative assets, at fair value	105
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | TBA Contracts [Member]
Derivative assets, at fair value	(844)	(12,694)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Payer Swaptions [Member]
Derivative assets, at fair value		72
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $4,521,136 and $3,885,554, respectively)	4,525,755	3,894,012
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $4,521,136 and $3,885,554, respectively)	0
Derivative asset, fair value		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] | Dual Digital Option [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
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Payer Swaptions [Member]
Derivative assets, at fair value		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $4,521,136 and $3,885,554, respectively)	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]
Mortgage-backed securities, at fair value (includes pledged assets of $4,521,136 and $3,885,554, respectively)	$ 0
Derivative asset, fair value		$ 0