Long-Term Debt and Credit Facilities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	9 Months Ended	12 Months Ended														9 Months Ended
	May 31, 2012	Aug. 31, 2012	Nov. 30, 2011	Apr. 30, 2012	Jun. 30, 2003	Aug. 31, 2012 Minimum	Aug. 31, 2012 Maximum	Aug. 31, 2012 Until second fiscal quarter of fiscal years 2013 Maximum	Aug. 31, 2012 From second fiscal quarter of fiscal years 2013 Maximum	Aug. 31, 2012 From second fiscal quarter of fiscal years 2013 Maximum	Aug. 31, 2012 Revolving Line Of Credit	Nov. 30, 2009 Unsecured Debt	May 31, 2012 Cash Borrowings	May 31, 2012 Letters Of Credit	Aug. 31, 2012 Letters Of Credit Revolving Line Of Credit	May 31, 2012 Swing Line Loans	Aug. 31, 2012 Mortgage Note	Aug. 31, 2012 Revenue Transactions	Aug. 31, 2012 Guarantee Credit Line
Line of Credit Facility [Line Items]
Mortgage note payable		$ 36.3	$ 38.1		$ 54.0
Mortgage note payable, amortization period (years)		20 years
Debt instrument, fixed annual interest rate				2.25%													5.50%
Debt principal balance																	34.4
Term on principal balance (in years)																	10 years
Minimum cash reserve for acquiring another company without consent of lender						50.0
Lines of credit facility potential maximum borrowings capacity	350.0
Revolving credit facility capacity											20.0	150.0	250.0	50.0	20.0	10.0			12.6
Unsecured revolving credit facility maturity date	Dec. 19, 2016
Lines of credit facility maximum borrowings capacity increase	100.0
Margin on base rate						0.25%	1.25%
Spread over LIBOR		1.00%				1.25%	2.25%
Margin on federal funds		0.50%
Loan origination fees and issuance costs		3.4
Credit facility amortized interest expense period (in years)		5 years
Default applicable interest rate on all obligations		2.00%
Interest coverage ratio						3.5
Leverage ratio								3.25	3.00	2.75
Revolving Line of credit maturity date											2013-06
Credit facility outstanding																	13.0	0.4
Bank guarantees		12.2	11.4
Restricted cash		$ 14.2	$ 13.8