Subsequent Event (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended		3 Months Ended	6 Months Ended
	May 31, 2012	Jan. 12, 2011	Jan. 31, 2011	Apr. 30, 2012
Line of Credit Facility [Line Items]
Aggregate principal amount of credit facilities	$ 1,000.0	$ 750.0
Original principal amount of term loan facility		250.0
Write-off debt issuance costs in interest expense	1.4
Existing debt issuance costs	6.0		0.5
Debt issuance costs incurred to refinance Credit Agreement	1.3		9.5
Line of credit facility maturity date				Jan. 12, 2016
Additional borrowing capacity	500.0	250.0
Maximum [Member]
Line of Credit Facility [Line Items]
Percentage of commitment fee on revolving credit facility	0.275%			0.50%
Percentage of margin on base rate loans	0.75%
Percentage of margin on adjusted foreign currency rate loans	1.75%
Minimum [Member]
Line of Credit Facility [Line Items]
Percentage of commitment fee on revolving credit facility	0.10%			0.15%
Percentage of margin on base rate loans	0.00%
Percentage of margin on adjusted foreign currency rate loans	1.00%
Revolving Credit Facilities [Member]
Line of Credit Facility [Line Items]
Aggregate principal amount of credit facilities		$ 750.0
Line of credit facility maturity date	May 31, 2017