Note 7 - Fair Value Measurements - Changes in Fair Value Due to Observable Factors (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair value, other assets	$ 31,762	$ 30,952
Fair value, other liabilities	0	0
Total realized gains included in income, other assets	183	199
Total realized gains included in income, other liabilities	0	0
Change in unrealized gains/losses included in other comprehensive income for assets and liabilities still held at September 30, other assets	0	0
Change in unrealized gains/losses included in other comprehensive income for assets and liabilities still held at September 30, other liabilities	0	0
Purchases, issuances and settlements, net, other assets	0	0
Purchases, issuances and settlements, net, other liabilities	0	0
Transfers out of Level 3, other assets	0	0
Transfers out of Level 3, other liabilities	0	0
Fair value, other assets	31,945	31,151
Fair value, other liabilities	0	0
Total realized gains included in income related to financial assets and liabilities still on the consolidated balance sheet, other assets	183	199
Total realized gains included in income related to financial assets and liabilities still on the consolidated balance sheet, other liabilities	$ 0	$ 0