DOCUMENT AND ENTITY INFORMATION	3 Months Ended
	Mar. 31, 2012	May 14, 2012
Entity Registrant Name	POTOMAC BANCSHARES INC
Entity Central Index Key	0000925173
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Trading Symbol	ptbs
Entity Common Stock, Shares Outstanding		3,390,178
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2012
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2012