Capital Stock and Stock-Based Awards (Details) (USD $)	12 Months Ended				12 Months Ended		49 Months Ended				12 Months Ended		12 Months Ended			12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2013 1995 Plan [Member]	May 31, 2013 2001 Plan [Member]	May 31, 2013 Plan 2011 [Member]	May 31, 2013 1997 Directors’ Plan [Member]	Sep. 30, 2011 2007 Directors’ Plan [Member]	May 31, 2013 2007 Directors’ Plan [Member]	Sep. 30, 2007 2007 Directors’ Plan [Member]	Sep. 30, 2012 Employee Stock Option [Member] Amended 2007 Directors Plan [Member]	May 31, 2013 Employee Stock Option [Member] Management Stock Purchase Plan [Member]	Sep. 30, 2012 Restricted Stock Units (RSUs) [Member] Amended 2007 Directors Plan [Member]	May 31, 2013 Restricted Stock Units (RSUs) [Member] Management Stock Purchase Plan [Member]	May 31, 2013 Restricted Stock Units (RSUs) [Member]	May 31, 2013 Class A Stock Options [Member]	Sep. 30, 2012 Amended 2007 Directors Plan [Member]	May 31, 2013 Management Stock Purchase Plan [Member]	May 31, 2012 Management Stock Purchase Plan [Member]	May 31, 2011 Management Stock Purchase Plan [Member]
Capital Stock and Stock-Based Awards (Details) [Line Items]
Non Qualified Stock Options To Purchase			174,500	1,646,897	581,376	6,000			3,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in Dollars per share)	$ 31.96				$ 31.96											$ 33.39
Common Stock Available For Additional Awards					1,253,908			285,551
Options To Purchase						132,000
Share Based Compensation Arrangement By Share Based Payment Award Restricted Stock Units							1,200									7,542
Non Qualified Stock Options To Purchase, Value (in Dollars)																$ 70,000
Non Qualified Stock Options To Purchase, Value Portion										40.00%		60.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	86,614															40,707
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	4,185,480	4,948,075						151,707							1,499,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized (in Dollars)	1,700,000												300,000	3,200,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition											2 years 73 days		2 years	2 years 146 days
Stock Issued During Period, Shares, Conversion of Units	242,433
Deferred Rate For Annual Cash Bonus Payment																	100.00%
Quarterly Basis Discount Rate Of Common Stock On Closing Price	15.00%																25.00%
Common Stock Remaining Authorized Under Management Stock Purchase Plan	451,922
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value (in Dollars)																	$ 6,400,000	$ 6,000,000	$ 4,100,000
Common Stock Remaining Authorized Under EmployeeS tock Purchase Plan	219,745