Note 18 - California First National Bancorp (Parent Only) Financial Information (Details) - Condensed Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 1,360	$ 1,678	$ 3,557	$ 2,459	$ 1,846	$ 1,190	$ 2,184	$ 1,831	$ 9,055	$ 7,051	$ 7,354
Adjustments to reconcile net earnings to cash flows:
Equity in undistributed earnings of subsidiaries									(3,959)	(3,189)	(5,280)
Other, net									37	673	(50)
Net cash provided by (used for) operating activities									5,169	6,466	(2,696)
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash (used for) provided by investing activities									(131,896)	(54,430)	(48,666)
CASH FLOWS FROM FINANCING ACTIVITIES:
Dividends paid									(4,393)	(4,179)	(22,985)
Net cash used for financing activities									146,845	12,617	69,910
NET CHANGE IN CASH AND CASH EQUIVALENTS									20,118	(35,347)	18,548
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD				40,122				75,469	40,122	75,469	56,921
CASH AND CASH EQUIVALENTS AT END OF PERIOD	60,240				40,122				60,240	40,122	75,469
Parent Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income									9,055	7,051	7,354
Adjustments to reconcile net earnings to cash flows:
Deferred income taxes									49	(706)	558
Equity in undistributed earnings of subsidiaries									(4,943)	(7,898)	(7,777)
Net change in other liabilities									(3)	74	(797)
Net change in other assets									510	37	(347)
Other, net									64	(68)	(25)
Net cash provided by (used for) operating activities									4,732	(1,510)	(1,034)
CASH FLOWS FROM INVESTING ACTIVITIES:
Payments for investments in and (advances to) subsidiaries									(44)	3,745	22,192
Net cash (used for) provided by investing activities									(44)	3,745	22,192
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock									0	156	164
Dividends paid									(4,393)	(4,179)	(22,985)
Net cash used for financing activities									(4,393)	(4,023)	(22,821)
NET CHANGE IN CASH AND CASH EQUIVALENTS									295	(1,788)	(1,663)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD				$ 2,796				$ 4,584	2,796	4,584	6,247
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 3,091				$ 2,796				$ 3,091	$ 2,796	$ 4,584