Income Taxes (Details 3)	12 Months Ended
May 31, 2011	May 31, 2010	May 31, 2009
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation Abstract
Statutory U.S. income tax rate	35.00%	35.00%	35.00%
Goodwill impairment			48.00%
State and local income taxes, net of federal benefit	1.70%	2.40%	1.90%
Other, net	(0.80%)	0.10%	0.70%
Effective tax rate	35.90%	37.50%	85.60%

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 Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 47

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Subparagraph 2
-Article 4

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- Definition

The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate shall be the regular tax rate if there are alternative tax systems.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 47

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to nondeductible impairment losses under enacted tax laws.

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to all other items not otherwise listed in the existing taxonomy.

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the state and local income tax expense (benefit), net of the federal tax benefit (expense) thereon, recorded during the period.

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