Note 11 - Fair Value of Financial Instruments and Fair Value Measurements - Fair Value Measurement Using Significant Unobservable Inputs (Details) - Available-for-sale Securities [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Balance, available for sale securities	$ 4,277	$ 7,298
Transfers out of Level 3		(2,009)
Maturities
Purchases
Paydowns	(390)	(886)
Unrealized Gains included in Other Comprehensive Income (Loss)	10	(126)
Balance, available for sale securities	$ 3,897	$ 4,277