Consolidated Statements of Income (Unaudited) (Parenthetical)	3 Months Ended	6 Months Ended
Jun. 29, 2012	Jun. 24, 2011	Jun. 29, 2012	Jun. 24, 2011
Consolidated Statements of Income [Abstract]
Limited partnership interest value (in dollars, per unit)	1,000	1,000	1,000	1,000

The per unit price of limited partnership interest, which represents the book value of each interest and has been arbitrarily determined.

No definition available.

Name:	jnfc_LimitedPartnershipInterestValuePerUnit
Namespace Prefix:	jnfc_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	duration