Document And Entity Information - USD ($)	12 Months Ended
	Jun. 30, 2015	Sep. 18, 2015	Dec. 31, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	CALIFORNIA FIRST NATIONAL BANCORP
Trading Symbol	cfnb
Document Type	10-K
Current Fiscal Year End Date	--06-30
Entity Common Stock, Shares Outstanding		10,459,924
Entity Public Float			$ 33,504,064
Amendment Flag	false
Entity Central Index Key	0000803016
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Well-known Seasoned Issuer	No
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY