Income taxes (Details) (USD $)	9 Months Ended
Jun. 30, 2012	Jun. 30, 2011
Income taxes [Abstract]
Effective tax rate	38.10%	38.50%
Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Amount of tax settlement	613,000
Interest accrued	225,000
Internal Revenue Service (IRS) [Member] \| Minimum [Member]
Income Tax Examination [Line Items]
Years under examination	2005
Internal Revenue Service (IRS) [Member] \| Maximum [Member]
Income Tax Examination [Line Items]
Years under examination	2007
State and Local Jurisdiction [Member]
Income Tax Examination [Line Items]
Penalties and interest due	435,000

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319

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-Publisher FASB

-Name Accounting Standards Codification

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

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- Definition

The amount of estimated interest accrued as of the balance sheet date arising from income tax examinations.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

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-Subparagraph (c)

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The amount of estimated penalties and interest accrued as of the balance sheet date arising from income tax examinations.

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- Definition

The tax year(s) being audited in connection with the income tax examination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

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-Subparagraph (d)(2)

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- Definition

Reflects the effects of adjustments of previously recorded tax expense, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, IRS tax settlement and unusual repatriation of foreign earnings.

+ References

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 48

-Paragraph 10

-Subparagraph b

-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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-Name FASB Interpretation (FIN)

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-Paragraph 10A, 10B, 10C

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