Note 11 - Regulatory Capital Ratios (Details Textual) - USD ($) $ in Millions		3 Months Ended
		Jun. 30, 2017	Dec. 31, 2016	Jan. 01, 2019	Mar. 31, 2017
Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	[1]	6.50%			6.50%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	[1]	8.00%			8.00%
Capital Required to be Well Capitalized to Risk Weighted Assets	[1]	10.00%			10.00%
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	[1]	5.00%			5.00%
Capital Conservation Buffer Phase In Period		4 years
Capital Conservation Buffer Level R Ratio		0.625%
Increase (Decrease) in Capital			$ 3
Self-imposed Internal Minimum Capital Level			8.00%
Scenario, Forecast [Member]
Capital Conservation Buffer Level R Ratio				2.50%

[1] Under prompt corrective action