Deposits - Summary of interest expense on deposits (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Deposits [Abstract]
Interest-bearing checking	$ 9	$ 9
Money Market	10	9
Savings	50	45
Time deposits, $100,000 or more	416	456
Time deposits below $100,000	815	962
Total Interest Expense	$ 1,300	$ 1,481

No definition available.

Name:	us-gaap_DepositsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate amount of all interest expense on domestic deposit liabilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.6)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

Name:	us-gaap_InterestExpenseDomesticDepositLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest expense on domestic money market demand account deposit liabilities.

+ References

+ Details

Name:	us-gaap_InterestExpenseDomesticDepositLiabilitiesMoneyMarket
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest expense on domestic notice of withdrawal demand deposit liabilities.

+ References

+ Details

Name:	us-gaap_InterestExpenseDomesticDepositLiabilitiesNoticeOfWithdrawal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest expense on domestic savings deposit liabilities.

+ References

+ Details

Name:	us-gaap_InterestExpenseDomesticDepositLiabilitiesSavings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest expense incurred on time deposits, including certificates of deposits, of $100,000 or more in domestic offices.

+ References

+ Details

Name:	us-gaap_InterestExpenseTimeDeposits100000OrMore
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest expense incurred on time deposits, including certificates of deposits, less than $100,000 in domestic offices.

+ References

+ Details

Name:	us-gaap_InterestExpenseTimeDepositsLessThan100000
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration