LOANS AND ALLOWANCE FOR LOAN LOSSES - Troubled Debt Restructurings (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) loan	Dec. 31, 2016 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of Contracts \| loan	3	3
Pre-Modification Outstanding Recorded Investment	$ 729,535	$ 399,176
Post-Modification Outstanding Recorded Investment	$ 729,535	399,176
Number of TDRs modified during the previous 12 months in default \| loan	0
Loans identified as TDRs	$ 2,228,270	1,824,206
TDRs on nonaccrual status	$ 1,876,109	$ 1,323,975
Loans Modified As TDRs [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| loan	3	3
Minimum
Financing Receivable, Modifications [Line Items]
Term of a loan deemed a TDR to perform to not be considered non-performing	6 months
The term of past due contractual payments for a TDR to be deemed in default	30 days
Residential Real Estate - Investor [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| loan		1
Pre-Modification Outstanding Recorded Investment		$ 35,672
Post-Modification Outstanding Recorded Investment		$ 35,672
Residential Real Estate - Investor [Member] \| TDR Loan A [Member]
Financing Receivable, Modifications [Line Items]
Interest rate reduction as a percent		4.75%
Interest rate		3.00%
Maturity date extension period		3 years
Residential Real Estate - Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| loan	3	2
Pre-Modification Outstanding Recorded Investment	$ 729,535	$ 363,504
Post-Modification Outstanding Recorded Investment	$ 729,535	$ 363,504
Residential Real Estate - Owner Occupied [Member] \| TDR Loan A [Member]
Financing Receivable, Modifications [Line Items]
Interest rate reduction as a percent	2.00%
Interest rate	5.50%
Residential Real Estate - Owner Occupied [Member] \| TDR Loan B [Member]
Financing Receivable, Modifications [Line Items]
Payment deferment period	6 months
Maturity date extension period		13 years
Term of restructured fixed-rate loan		20 years
Residential Real Estate - Owner Occupied [Member] \| TDR Loan C [Member]
Financing Receivable, Modifications [Line Items]
Interest rate	3.85%
Payment deferment period		1 month
Maturity date extension period	11 years	1 month
Period of reduced payments		11 months

BAY BANCORP, INC. 10-K