Note 4 - Loans Receivable - Past Due and Nonaccrual Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Loans receivable, current	$ 1,644,633	$ 1,542,854
Loans receivable, gross	1,658,444	1,555,904
Nonaccrual [Member]
Loans receivable, current	6,556	10,714
Loans receivable, gross	16,426	17,376
Financing Receivables 30 to 89 Days Past Due [Member]
Loans receivable, past due	4,474	7,228
Financing Receivables 30 to 89 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	1,047	1,610
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	9,337	5,822
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	8,823	5,052
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member]
Loans receivable, current	391,619	381,885
Loans receivable, gross	396,550	389,107
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Nonaccrual [Member]
Loans receivable, current	4,096	3,183
Loans receivable, gross	6,866	6,709
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans receivable, past due	2,352	4,472
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Financing Receivables 30 to 89 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	387	1,194
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	2,579	2,750
Real Estate Portfolio Segment [Member] | One-to-Four-Family Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	2,383	2,332
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member]
Loans receivable, current	96,206	92,341
Loans receivable, gross	96,325	92,460
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Nonaccrual [Member]
Loans receivable, current
Loans receivable, gross	119
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans receivable, past due		119
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Financing Receivables 30 to 89 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	119
Real Estate Portfolio Segment [Member] | Multifamily Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	119
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member]
Loans receivable, current	529,762	492,205
Loans receivable, gross	535,824	495,173
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Nonaccrual [Member]
Loans receivable, current	1,606	3,927
Loans receivable, gross	7,172	5,177
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans receivable, past due	996	1,651
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables 30 to 89 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	626	94
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	5,066	1,317
Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	4,940	1,156
Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans receivable, current	96,670	93,238
Loans receivable, gross	97,881	94,018
Real Estate Portfolio Segment [Member] | Farmland [Member] | Nonaccrual [Member]
Loans receivable, current	173	92
Loans receivable, gross	1,023	783
Real Estate Portfolio Segment [Member] | Farmland [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans receivable, past due	361	131
Real Estate Portfolio Segment [Member] | Farmland [Member] | Financing Receivables 30 to 89 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due		41
Real Estate Portfolio Segment [Member] | Farmland [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	850	649
Real Estate Portfolio Segment [Member] | Farmland [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	850	650
Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable, current	130,699	125,243
Loans receivable, gross	131,046	125,785
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Nonaccrual [Member]
Loans receivable, current	84
Loans receivable, gross	212	463
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans receivable, past due	143	20
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables 30 to 89 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due		13
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	204	522
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	128	450
Commercial Portfolio Segment [Member]
Loans receivable, current	363,484	322,180
Loans receivable, gross	364,194	323,096
Commercial Portfolio Segment [Member] | Nonaccrual [Member]
Loans receivable, current	550	3,456
Loans receivable, gross	844	4,071
Commercial Portfolio Segment [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans receivable, past due	322	413
Commercial Portfolio Segment [Member] | Financing Receivables 30 to 89 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	22	229
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	388	503
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	272	386
Consumer Portfolio Segment [Member]
Loans receivable, current	36,193	35,762
Loans receivable, gross	36,624	36,265
Consumer Portfolio Segment [Member] | Nonaccrual [Member]
Loans receivable, current	47	56
Loans receivable, gross	190	173
Consumer Portfolio Segment [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans receivable, past due	300	422
Consumer Portfolio Segment [Member] | Financing Receivables 30 to 89 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	12	39
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	131	81
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Nonaccrual [Member]
Loans receivable, past due	$ 131	$ 78