Note 5 - Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Accrual [Member]
Financing Receivable, Modifications, Number of Contracts	2	2
Financing Receivable, Modifications, Recorded Investment	$ 203	$ 205
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Nonaccrual [Member]
Financing Receivable, Modifications, Number of Contracts	6	6
Financing Receivable, Modifications, Recorded Investment	$ 338	$ 450
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member]
Financing Receivable, Modifications, Number of Contracts	8	8
Financing Receivable, Modifications, Recorded Investment	$ 541	$ 655
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Accrual [Member]
Financing Receivable, Modifications, Number of Contracts
Financing Receivable, Modifications, Recorded Investment
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Nonaccrual [Member]
Financing Receivable, Modifications, Number of Contracts	3	3
Financing Receivable, Modifications, Recorded Investment	$ 447	$ 461
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member]
Financing Receivable, Modifications, Number of Contracts	3	3
Financing Receivable, Modifications, Recorded Investment	$ 447	$ 461
Real Estate Portfolio Segment [Member] | Farmland [Member] | Accrual [Member]
Financing Receivable, Modifications, Number of Contracts
Financing Receivable, Modifications, Recorded Investment
Real Estate Portfolio Segment [Member] | Farmland [Member] | Nonaccrual [Member]
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Modifications, Recorded Investment	$ 250	$ 250
Real Estate Portfolio Segment [Member] | Farmland [Member]
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Modifications, Recorded Investment	$ 250	$ 250
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Accrual [Member]
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Modifications, Recorded Investment	$ 78	$ 79
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Nonaccrual [Member]
Financing Receivable, Modifications, Number of Contracts	2	2
Financing Receivable, Modifications, Recorded Investment	$ 235	$ 242
Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Modifications, Number of Contracts	3	3
Financing Receivable, Modifications, Recorded Investment	$ 313	$ 321
Consumer Portfolio Segment [Member] | Accrual [Member]
Financing Receivable, Modifications, Number of Contracts
Financing Receivable, Modifications, Recorded Investment
Consumer Portfolio Segment [Member] | Nonaccrual [Member]
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Modifications, Recorded Investment	$ 5	$ 5
Consumer Portfolio Segment [Member]
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Modifications, Recorded Investment	$ 5	$ 5
Commercial Portfolio Segment [Member] | Accrual [Member]
Financing Receivable, Modifications, Number of Contracts
Financing Receivable, Modifications, Recorded Investment
Commercial Portfolio Segment [Member] | Nonaccrual [Member]
Financing Receivable, Modifications, Number of Contracts		1
Financing Receivable, Modifications, Recorded Investment		$ 21
Commercial Portfolio Segment [Member]
Financing Receivable, Modifications, Number of Contracts		1
Financing Receivable, Modifications, Recorded Investment		$ 21
Accrual [Member]
Financing Receivable, Modifications, Number of Contracts	3	3
Financing Receivable, Modifications, Recorded Investment	$ 281	$ 284
Nonaccrual [Member]
Financing Receivable, Modifications, Number of Contracts	13	14
Financing Receivable, Modifications, Recorded Investment	$ 1,275	$ 1,429
Financing Receivable, Modifications, Number of Contracts	16	17
Financing Receivable, Modifications, Recorded Investment	$ 1,556	$ 1,713