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	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Balance, available for sale securities	$ 7,298	$ 576
Transfers out of Level 3
Maturities		(360)
Loss on OTTI Impairment Included in Noninterest Income
Purchases		7,070
Paydowns	(327)
Balance, available for sale securities	$ 6,825	$ 7,298