Note 5 - Fair Value Measurements - Fair Value Reconciliation of Level 3 Assets (Details) - Subordinated Debt Obligations [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)
Balance as of January 1, 2023	$ 8,737
Transfers into Level III (1)	0	[1]
Transfers out of Level III (1)	0	[1]
Net change in unrealized loss on available-for-sale investment securities	69
Balance as of March 31, 2023	$ 8,806

[1] Transfers between hierarchy levels are based on the availability of sufficient observable inputs to meet Level II versus Level II criteria. The level designation of each financial instrument is reassessed at the end of each period.