Note 5 - Loans Receivable - Loans Restructured as TDRs (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)		Dec. 31, 2015
Number of Loans		1		4		0
Balance prior to TDR		$ 642		$ 4,572
Balance		623		4,534
Modification of Payment Terms [Member]
Balance		$ 642	[1]	$ 4,572	[2]
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member]
Number of Loans		1		1
Balance prior to TDR		$ 642		$ 4,244
Balance		623		4,244
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Modification of Payment Terms [Member]
Balance		$ 642	[1]	$ 4,244	[2]
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member]
Number of Loans				1
Balance prior to TDR				$ 5
Balance				2
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Modification of Payment Terms [Member]
Balance	[2]			$ 5
Commercial Portfolio Segment [Member]
Number of Loans				2
Balance prior to TDR				$ 323
Balance				288
Commercial Portfolio Segment [Member] | Modification of Payment Terms [Member]
Balance	[2]			$ 323

[1] The borrower's payment was lowered for the remainder of the term resulting in an extended amortization term.

[2] Concessions represent skipped payments/maturity date extensions, amortization term extensions.