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Loans and Allowance for Loan Losses - Additional Information (Details)	9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) Loan	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) Loan
Financing Receivable Recorded Investment [Line Items]
Loans past due 90 days and still on accrual	$ 0		$ 0
Interest income recognized on cash basis	$ 0	$ 0	$ 0
Number of loans identified as troubled debt restructurings | Loan	5		6
Specific reserve	$ 11,420,000		$ 14,162,000
Commitments to lend an additional amounts of outstanding loans are classified as TDR's	$ 0		0
Description of loans modified as troubled debt restructuring	During the year ended December 31, 2016 and for the nine months ended September 30, 2017, the terms of certain loans were modified as TDR's. The modification of the terms generally included loans where a moratorium on loan payments was granted. Such moratoriums ranged from three months to twelve months on the loans restructured in 2017 and 2016.
Increase in allowance for loan losses under purchased credit-impaired loans	$ 0		0
Significant reductions in allowance for loan losses under purchased credit-impaired loans	$ 0		0
Minimum
Financing Receivable Recorded Investment [Line Items]
Moratorium on loan payments period granted	3 months
Maximum
Financing Receivable Recorded Investment [Line Items]
Moratorium on loan payments period granted	12 months
One Loan
Financing Receivable Recorded Investment [Line Items]
Specific reserve	$ 0		$ 1,782,000

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Certain loans acquired in transfer not accounted for as debt securities allowance for loan losses increases.

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Moratorium on loan payment period granted.

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Amount of allowance for credit losses related to receivables which had been measured under a general allowance for credit losses methodology that are now identified as troubled debt restructurings.

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Amount of reduction in the reserve for loans impairments as a result of current information and events which result in it being probable that estimated cash flows will be significantly higher than previously expected or because actual cash flows are significantly greater than cash flows previously expected for loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Description of the nature and the extent of troubled debt restructurings that occurred during the period related to financing receivables.

+ 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=84173941&loc=SL6953676-111524

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

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-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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Recorded investment in financing receivables that are 90 days or more past due and still accruing.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
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Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
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Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18794-111554

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