Loans - Performing, Past Due and Adversely Classified Loan Balances by Loan Classification (Detail) - USD ($)	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	$ 525,635,000	$ 529,607,000
30 - 89 Days Past Due	2,939,000	1,855,000
90 Days Plus Past Due and Still Accruing	2,679,000	0	$ 0
Non-accrual Loans	11,523,000	7,422,000	7,056,000
Special Mention	1,451,000	2,958,000
Impaired Loans Currently Performing Substandard	23,440,000	20,652,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	567,667,000	562,494,000
Multi-Family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	26,460,000	21,638,000
30 - 89 Days Past Due		6,000
Non-accrual Loans	1,772,000	1,968,000	1,827,000
Impaired Loans Currently Performing Substandard	3,057,000	1,113,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	31,289,000	24,725,000
One-to-Four Family Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	141,856,000	142,058,000
30 - 89 Days Past Due	1,037,000	671,000
90 Days Plus Past Due and Still Accruing	283,000
Non-accrual Loans	469,000	2,234,000	1,456,000
Special Mention	753,000	41,000
Impaired Loans Currently Performing Substandard	1,461,000	995,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	145,859,000	145,999,000
Home Equity Line of Credit [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	32,594,000	33,396,000
30 - 89 Days Past Due	173,000	79,000
Non-accrual Loans	54,000	48,000	48,000
Special Mention	21,000
Impaired Loans Currently Performing Substandard	221,000	121,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	33,063,000	33,644,000
Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	36,923,000	34,878,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	36,923,000	34,878,000
Land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	9,558,000	11,047,000
30 - 89 Days Past Due	766,000	747,000
90 Days Plus Past Due and Still Accruing	1,236,000
Non-accrual Loans	8,281,000	1,553,000	1,982,000
Special Mention	38,000	41,000
Impaired Loans Currently Performing Substandard	2,002,000	9,065,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	21,881,000	22,453,000
Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	43,808,000	41,853,000
30 - 89 Days Past Due	701,000	64,000
Non-accrual Loans		166,000	209,000
Impaired Loans Currently Performing Substandard	1,084,000	163,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	45,593,000	42,246,000
Non-Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	144,029,000	138,637,000
30 - 89 Days Past Due	47,000	228,000
90 Days Plus Past Due and Still Accruing	1,160,000
Non-accrual Loans	28,000	247,000	520,000
Special Mention	282,000	2,489,000
Impaired Loans Currently Performing Substandard	9,112,000	8,110,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	154,658,000	149,711,000
Junior Liens [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	1,616,000	1,720,000
Special Mention	33,000	35,000
Impaired Loans Currently Performing Substandard	12,000	16,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	1,661,000	1,771,000
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	8,207,000	20,108,000
30 - 89 Days Past Due	22,000	15,000
Non-accrual Loans	31,000	8,000
Impaired Loans Currently Performing Substandard	222,000	193,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	8,482,000	20,324,000
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Currently Performing	80,584,000	84,272,000
30 - 89 Days Past Due	193,000	45,000
Non-accrual Loans	888,000	1,198,000	$ 1,014,000
Special Mention	324,000	352,000
Impaired Loans Currently Performing Substandard	6,269,000	876,000
Impaired Loans Currently Performing Doubtful	0	0
Total loans, gross	$ 88,258,000	$ 86,743,000