Note 10 - Credit Quality of Financing Receivables and Allowance for Credit Losses (Details Textual)	3 Months Ended
Sep. 30, 2016
Number of Days Past Due on Lease or Loan Payments Minimum	90 days

Minimum number of days customer is past due on its lease or loan payments, causing the accrual of interest income to be discontinued.

No definition available.

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Namespace Prefix:	cfnb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration