Share-based Compensation Plans (Detail) - Share-based compensation plans activity	12 Months Ended
Dec. 29, 2012	Dec. 31, 2011
Service Based Grants [Member]
Outstanding	597,900
Outstanding	36 days	73 days
Unvested shares expected to vest as of December 29, 2012**	36,800
Unvested shares expected to vest as of December 29, 2012**	1 year 328 days
Exercisable/unrestricted	468,400
Granted	16,100
Exercised/units settled	(147,800)
Shares deferred upon vesting/settlement & dividend equivalents on deferred shares*	46,000
Outstanding	512,200	597,900
Exercisable/unrestricted	475,400	468,400
Performance Based Grants [Member]
Outstanding	568,200
Outstanding	328 days	255 days
Unvested shares expected to vest as of December 29, 2012**	294,600
Unvested shares expected to vest as of December 29, 2012**	1 year 219 days
Exercisable/unrestricted	319,900
Granted	232,300
Forfeited/cancelled	(142,000)
Exercised/units settled	(26,700)
Shares deferred upon vesting/settlement & dividend equivalents on deferred shares*	9,900
Outstanding	641,700	568,200
Exercisable/unrestricted	303,100	319,900

Number of non-option equity instruments deferred upon vesting.

No definition available.

Name:	nafc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsDeferredUponVesting
Namespace Prefix:	nafc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares into which expected to vest non options equity instruments outstanding can be converted under the plan.

+ References

No definition available.

+ Details

Name:	nafc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpectedToVestOutstandingNumber
Namespace Prefix:	nafc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average remaining contractual term for equity-based awards excluding options for instruments expected to be vested, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	nafc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpectedToVestOutstandingNumberWeightedAverageRemainingContractualTerm
Namespace Prefix:	nafc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of non-option equity instruments exercised by participants.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares under non-option equity instrument agreements that were cancelled as a result of occurrence of a terminating event.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Net number of non-option equity instruments granted to participants.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares reserved for issuance under non-option equity instrument agreements awarded that validly exist and are outstanding, including vested instruments.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph d(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant