Summary of Financial Effects of Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($) Investment	Dec. 31, 2015 USD ($) Investment	Dec. 31, 2014 USD ($) Investment
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment	13	8	8
Trouble debt restructuring, charge-off amount \| $	$ 170	$ 33	$ 352
Capitalized interest \| $	$ 11	$ 8	$ 22
Multi-Family
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment	1		2
Weighted Average Interest Rate, Pre-Modification	4.63%		5.61%
Weighted Average Interest Rate, Post-Modification	4.00%		5.61%
One-to-four family
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment	5	4	1
Weighted Average Interest Rate, Pre-Modification	4.26%	4.02%	5.75%
Weighted Average Interest Rate, Post-Modification	2.65%	2.72%	4.27%
Trouble debt restructuring, charge-off amount \| $			$ 18
Capitalized interest \| $	$ 11	$ 6	$ 22
Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment	7	2	1
Weighted Average Interest Rate, Pre-Modification	3.22%	3.40%	5.00%
Weighted Average Interest Rate, Post-Modification	3.19%	3.52%	5.00%
Trouble debt restructuring, charge-off amount \| $	$ 170	$ 33
Other loans
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment		2
Weighted Average Interest Rate, Pre-Modification		4.58%
Weighted Average Interest Rate, Post-Modification		2.00%
Capitalized interest \| $		$ 2
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment			2
Weighted Average Interest Rate, Pre-Modification			6.71%
Weighted Average Interest Rate, Post-Modification			5.54%
Trouble debt restructuring, charge-off amount \| $			$ 334
Acquisition, Development and Construction
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment			2
Weighted Average Interest Rate, Pre-Modification			7.00%
Weighted Average Interest Rate, Post-Modification			7.00%

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Weighted Average Interest Rate Pre Modification

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953676-111524

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Reflects the amount of the write-down related to a troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

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The gross interest income that would have been recorded in the period on troubled debt restructurings, if the loans had been current in accordance with their original terms and had been outstanding throughout the period or since origination, if held for part of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18794-111554

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