Impairment of Long-Lived Assets and Goodwill - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
Mar. 31, 2013 Restaurant	Sep. 30, 2012
Impaired Long-Lived Assets Held and Used [Line Items]
Projected variable and semi-variable restaurant operating costs increase percentage	1.50%
Projected food and packaging costs decrease percentage		0.50%
Number of restaurants impaired	0
Goodwill	$ 96,000
Minimum
Impaired Long-Lived Assets Held and Used [Line Items]
Historical weighted average menu price increase percentage	1.50%
Projected fixed restaurant operating costs increase percentage	1.50%
Maximum
Impaired Long-Lived Assets Held and Used [Line Items]
Historical weighted average menu price increase percentage	6.00%
Projected fixed restaurant operating costs increase percentage	2.00%
Projected cash flows decline percentage	15.00%
Fiscal Year 2013
Impaired Long-Lived Assets Held and Used [Line Items]
Projected sales increase percentage	6.00%
Fiscal Year Twenty Fourteen To Twenty Twenty Seven \| Minimum
Impaired Long-Lived Assets Held and Used [Line Items]
Projected sales increase percentage	2.00%
Fiscal Year Twenty Fourteen To Twenty Twenty Seven \| Maximum
Impaired Long-Lived Assets Held and Used [Line Items]
Projected sales increase percentage	3.00%

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-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.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

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-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.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

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-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.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 72

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-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.

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