Note 3 - Loans Held for Investment, Net - Geographies and Property Types of Collateral Underlying the Loans Held-for-investment as a Percentage of the Loans' Face Amounts (Details)	Mar. 31, 2022	Dec. 31, 2021
% of loan portfolio	100.00%	100.00%
Single Family Rental [Member]
% of loan portfolio	67.77%	76.15%
Multifamily [Member]
% of loan portfolio	28.99%	20.32%
Life Science [Member]
% of loan portfolio	3.24%	3.53%
GEORGIA
% of loan portfolio	30.51%	38.93%
FLORIDA
% of loan portfolio	16.75%	16.90%
TEXAS
% of loan portfolio	7.82%	7.74%
NEVADA
% of loan portfolio	6.12%
MARYLAND
% of loan portfolio	5.72%	5.66%
MINNESOTA
% of loan portfolio	4.91%	4.86%
NEW YORK
% of loan portfolio	4.33%
CALIFORNIA
% of loan portfolio	4.29%	2.53%
ALABAMA
% of loan portfolio	3.39%	3.35%
NEW JERSEY
% of loan portfolio	2.86%	2.83%
NORTH CAROLINA
% of loan portfolio	2.27%	2.23%
MISSOURI
% of loan portfolio	1.20%	1.19%
CONNECTICUT
% of loan portfolio		2.87%
Other [Member]
% of loan portfolio	9.83%	10.91%