Fair Value - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 69,778	$ 59,724
Investment securities	27,144	28,897
Loans receivable, net	918,509	798,703
Accrued interest receivable	3,795	3,335
FHLB stock	2,915	1,511
Demand deposits	115,923	103,001
Interest-bearing deposits	269,749	200,923
Certificates of deposit	424,086	410,061
Advance payments by borrowers for taxes and insurance	6,037	5,025
Advances	69,404	36,400
Accrued interest payable	63	42
Fair Value Measurements
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	69,778	59,724
Investment securities	27,144	28,897
Loans receivable, net	926,867	813,160
Accrued interest receivable	3,795	3,335
FHLB stock	2,915	1,511
Demand deposits	115,923	103,001
Interest-bearing deposits	269,749	200,923
Certificates of deposit	425,564	414,902
Advance payments by borrowers for taxes and insurance	6,037	5,025
Advances	69,404	36,400
Accrued interest payable	63	42
Fair Value Measurements \| Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	69,778	59,724
Investment securities	4,995
FHLB stock	2,915	1,511
Demand deposits	115,923	103,001
Interest-bearing deposits	269,749	200,923
Advances	69,404	36,400
Fair Value Measurements \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investment securities	22,149	28,897
Accrued interest receivable	3,795	3,335
Certificates of deposit	425,564	414,902
Advance payments by borrowers for taxes and insurance	6,037	5,025
Accrued interest payable	63	42
Fair Value Measurements \| Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans receivable, net	$ 926,867	$ 813,160

Accrued interest payable fair value.

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- Definition

Accrued interest receivable fair value.

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Advance payments by borrowers for taxes and insurance fair value.

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- Definition

Advances from Federal Home Loan Banks and Zions Bank fair value disclosure.

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- Definition

Certificates of deposit fair value.

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Demand deposit liability fair value.

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Federal home loan bank stock fair value.

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- Definition

Interest bearing deposit fair value.

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

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