Note 2 - Investment Securities (Details Textual) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Corporate Debt Securities [Member]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	9	13
Available for Sale Securities, Continuous Unrealized Loss Position, Aggregate Depreciation from Amortized Cost Basis	2.56%	1.76%
Mortgage-backed Securities and Collateralized Mortgage Obligations [Member]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	8	20
Available for Sale Securities, Continuous Unrealized Loss Position, Aggregate Depreciation from Amortized Cost Basis	0.87%	1.57%
US Government Agencies Debt Securities [Member]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	15	52
Available for Sale Securities, Continuous Unrealized Loss Position, Aggregate Depreciation from Amortized Cost Basis	0.85%	1.43%
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	32	85
Expected Credit Loss on Securities	$ 0