Note 6 - Fair Values of Assets and Liabilities - Summary of Other Relevant Data (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Loans, interest and fees receivable, at fair value	$ 846,160	$ 417,098
Loans and Fees Receivable at Fair Value [Member]
Aggregate unpaid gross balance of loans, interest and fees receivable that are reported at fair value	1,850	630
Aggregate unpaid principal balance included within loans, interest and fees receivable that are reported at fair value	1,774	589
Loans, interest and fees receivable, at fair value	1,485	540
Aggregate fair value of receivables carried at fair value that are 90 days or more past due (which also coincides with finance charge and fee non-accrual policies)	9	1
Unpaid principal balance of receivables within loans, interest and fees receivable that are reported at fair value and are 90 days or more past due (which also coincides with finance charge and fee non-accrual policies) over the fair value of such loans, interest and fees receivable	31	4
Structured Financing Notes Payable [Member]
Aggregate unpaid principal balance included within loans, interest and fees receivable that are reported at fair value	101,314	101,314
Aggregate fair value of notes payable	2,221	2,919
Loans and Fees Receivable Pledged as Collateral, Fair Value [Member]
Aggregate unpaid gross balance of loans, interest and fees receivable that are reported at fair value	1,026,517	515,434
Aggregate unpaid principal balance included within loans, interest and fees receivable that are reported at fair value	951,905	487,779
Loans, interest and fees receivable, at fair value	844,675	416,558
Aggregate fair value of receivables carried at fair value that are 90 days or more past due (which also coincides with finance charge and fee non-accrual policies)	2,199	1,847
Unpaid principal balance of receivables within loans, interest and fees receivable that are reported at fair value and are 90 days or more past due (which also coincides with finance charge and fee non-accrual policies) over the fair value of such loans, interest and fees receivable	$ 34,576	$ 12,972