Fair Values of Financial Instruments - Schedule of Quantitative Information About Level 3 Fair Value Measurements (Details) - Nonrecurring - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	$ 1,103,000	$ 0
Level 3
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	1,103,000
Impaired residential mortgage loan
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	58,000
Impaired residential mortgage loan \| Level 3
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	$ 58,000
Range	10.00%
Impaired commercial real estate loan
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	$ 463,000
Impaired commercial real estate loan \| Level 3
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	$ 463,000
Range	37.00%
Impaired commercial business loan
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	$ 582,000
Impaired commercial business loan \| Level 3
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	$ 582,000
Range	64.00%

Percentage of adjustment to the observed price for a similar asset or liability when an identical transaction does not exist, used as an input to measure fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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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.

+ References

No definition available.

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- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

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