Loans Receivable, Net - Allowance for Loan Loss Account by Loan (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				$ 4,826				$ 6,112	$ 4,826	$ 6,112	$ 5,700
Charge off									(707)	(3,159)	(1,468)
Recoveries									129	1,396	639
Provision for Loan Loss	$ 84	$ 74	$ 62	68	$ 56	$ 71	$ 59	291	288	477	1,241
Ending balance	4,536				4,826				4,536	4,826	6,112
Multi-Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				314				412	314	412	227
Charge off											(421)
Recoveries										417
Provision for Loan Loss									(142)	(515)	606
Ending balance	172				314				172	314	412
One-to-Four Family Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				747				852	747	852	1,030
Charge off									(6)	(66)
Recoveries									13	13	167
Provision for Loan Loss									238	(52)	(345)
Ending balance	992				747				992	747	852
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				189				260	189	260	201
Charge off											(30)
Recoveries									9	12	14
Provision for Loan Loss									(30)	(83)	75
Ending balance	168				189				168	189	260
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				161				277	161	277	377
Provision for Loan Loss									10	(116)	(100)
Ending balance	171				161				171	161	277
Land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				1,223				1,760	1,223	1,760	1,379
Charge off									(40)	(2,608)
Recoveries										559
Provision for Loan Loss									(386)	1,512	381
Ending balance	797				1,223				797	1,223	1,760
Non-Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				789				964	789	964	1,139
Charge off									(23)
Recoveries									14	16	10
Provision for Loan Loss									513	(191)	(185)
Ending balance	1,293				789				1,293	789	964
Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				367				778	367	778	358
Charge off									(2)
Recoveries									1	10
Provision for Loan Loss									(214)	(421)	420
Ending balance	152				367				152	367	778
Junior Liens [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				5				8	5	8	8
Recoveries										4	14
Provision for Loan Loss									(1)	(7)	(14)
Ending balance	4				5				4	5	8
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				184				208	184	208	358
Charge off									(329)	(261)	(422)
Recoveries									80	87	293
Provision for Loan Loss									177	150	(21)
Ending balance	112				184				112	184	208
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance				$ 847				$ 593	847	593	623
Charge off									(307)	(224)	(595)
Recoveries									12	278	141
Provision for Loan Loss									123	200	424
Ending balance	$ 675				$ 847				$ 675	$ 847	$ 593