Condensed Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Pledged assets, Mortgage-backed securities	$ 4,525,755	$ 3,894,012
U.S. Treasury securities, available for sale, amortized cost	98,092	148,803
Pledged assets, available for sale	$ 98,099	$ 148,820
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	20,000,000	20,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	100,000,000	100,000,000
Common stock, issued (in shares)	64,824,374	51,636,074
Common stock, outstanding (in shares)	64,824,374	51,636,074
Asset Pledged as Collateral [Member]
Pledged assets, Mortgage-backed securities	$ 4,521,136	$ 3,885,554
Pledged assets, available for sale	$ 78,430	$ 79,680