Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 02, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2019
Entity Registrant Name	SB ONE BANCORP
Entity Central Index Key	0001028954
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Accelerated Filer
Trading Symbol	sbbx
Entity Common Stock, Shares Outstanding		9,475,378