Loans and Allowance for Loan Losses - Troubled Debt Restructurings (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) loan	Mar. 31, 2018 loan	Dec. 31, 2018 USD ($)
Loans Modified as TDRs as of Period End [Abstract]
Accruing	$ 412,000		$ 432,000
Nonaccrual	127,000		131,000
Total	$ 539,000		563,000
Loans Modified as TDRs During the Period [Abstract]
Number of new loans modified as TDRs | loan	0	0
Number of commitments to lend to customers with outstanding loans that were classified as TDRs	$ 0		0
Allowance for loan losses	84,000		86,000
Real Estate | SBA property
Loans Modified as TDRs as of Period End [Abstract]
Accruing	310,000		315,000
Nonaccrual	0		0
Total	310,000		315,000
Commercial and Industrial | Commercial term
Loans Modified as TDRs as of Period End [Abstract]
Accruing	57,000		68,000
Nonaccrual	0		0
Total	57,000		68,000
Commercial and Industrial | SBA commercial term
Loans Modified as TDRs as of Period End [Abstract]
Accruing	45,000		49,000
Nonaccrual	127,000		131,000
Total	$ 172,000		$ 180,000