Loans - Loans by Class Modified as Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017 USD ($) Loan	Sep. 30, 2018 USD ($) Loan	Sep. 30, 2017 USD ($) Loan
Financing Receivable Modifications [Line Items]
Number of Loans \| Loan	1	6	3
Pre-Modification Outstanding Recorded Investment	$ 147	$ 758	$ 337
Post-Modification Recorded Investment	$ 169	$ 784	$ 368
Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Loans \| Loan		1
Pre-Modification Outstanding Recorded Investment		$ 124
Post-Modification Recorded Investment		$ 124
Commercial Loans [Member] \| Nonresidential [Member]
Financing Receivable Modifications [Line Items]
Number of Loans \| Loan		1
Pre-Modification Outstanding Recorded Investment		$ 124
Post-Modification Recorded Investment		$ 124
Residential Mortgage Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Loans \| Loan	1	3	2
Pre-Modification Outstanding Recorded Investment	$ 147	$ 521	$ 222
Post-Modification Recorded Investment	$ 169	$ 547	$ 253
Residential Mortgage Loans [Member] \| One-to Four-Family [Member]
Financing Receivable Modifications [Line Items]
Number of Loans \| Loan	1	3	2
Pre-Modification Outstanding Recorded Investment	$ 147	$ 521	$ 222
Post-Modification Recorded Investment	$ 169	$ 547	$ 253
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Loans \| Loan		2	1
Pre-Modification Outstanding Recorded Investment		$ 113	$ 115
Post-Modification Recorded Investment		$ 113	$ 115
Consumer Loans [Member] \| Home Equity [Member]
Financing Receivable Modifications [Line Items]
Number of Loans \| Loan		2
Pre-Modification Outstanding Recorded Investment		$ 113
Post-Modification Recorded Investment		$ 113
Consumer Loans [Member] \| Recreational Vehicle [Member]
Financing Receivable Modifications [Line Items]
Number of Loans \| Loan			1
Pre-Modification Outstanding Recorded Investment			$ 115
Post-Modification Recorded Investment			$ 115

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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