Note 5 - Loans Receivable - Loans by Risk Categories (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans receivable	$ 1,672,859	$ 1,555,904
Pass [Member]
Loans receivable	1,605,634	1,502,512
Special Mention [Member]
Loans receivable	18,477	521
Substandard [Member]
Loans receivable	48,748	52,871
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member]
Loans receivable	391,225	389,107
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Pass [Member]
Loans receivable	379,407	375,287
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Special Mention [Member]
Loans receivable	150	206
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Substandard [Member]
Loans receivable	11,668	13,614
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member]
Loans receivable	89,087	92,460
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Pass [Member]
Loans receivable	89,087	92,460
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Special Mention [Member]
Loans receivable
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Substandard [Member]
Loans receivable
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member]
Loans receivable	557,185	495,173
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Pass [Member]
Loans receivable	543,427	473,343
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Special Mention [Member]
Loans receivable	287	314
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Substandard [Member]
Loans receivable	13,471	21,516
Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans receivable	96,786	94,018
Real Estate Portfolio Segment [Member] | Farmland [Member] | Pass [Member]
Loans receivable	95,114	92,131
Real Estate Portfolio Segment [Member] | Farmland [Member] | Special Mention [Member]
Loans receivable
Real Estate Portfolio Segment [Member] | Farmland [Member] | Substandard [Member]
Loans receivable	1,672	1,887
Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	157,453	125,785
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Pass [Member]
Loans receivable	148,927	116,269
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Special Mention [Member]
Loans receivable
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Substandard [Member]
Loans receivable	8,526	9,516
Commercial Portfolio Segment [Member]
Loans receivable	345,087	323,096
Commercial Portfolio Segment [Member] | Pass [Member]
Loans receivable	314,028	317,069
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans receivable	18,040
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans receivable	13,019	6,027
Consumer Portfolio Segment [Member]
Loans receivable	36,036	36,265
Consumer Portfolio Segment [Member] | Pass [Member]
Loans receivable	35,644	35,953
Consumer Portfolio Segment [Member] | Special Mention [Member]
Loans receivable		1
Consumer Portfolio Segment [Member] | Substandard [Member]
Loans receivable	$ 392	$ 311