Debt (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended	0 Months Ended			0 Months Ended
	May 31, 2012	Jan. 31, 2013	May 31, 2012 Minimum [Member]	May 31, 2012 Maximum [Member]	Jan. 12, 2011 Revolving Credit Facilities [Member]	May 31, 2012 Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, initiation date		Jan. 12, 2011
Aggregate commitment amount of credit facilities					$ 1,000,000,000
Additional borrowings						500,000,000
Expiration date						May 31, 2017
Commitment fee percentage			0.10%	0.275%
Line of credit facility interest rate margin on base rate loans percentage			0.00%	0.75%
Line of credit facility interest rate margin on foreign currency loans percentage			1.00%	1.75%
Required minimum Interest coverage ratio	3.00
Required maximum total leverage ratio	3.75
Interest Coverage Ratio		43.55
Total Leverage Ratio		0.88
Amount available under the credit agreement		624,000,000
Write-off debt issuance costs in interest expense	1,400,000
Existing debt issuance costs	6,000,000
Debt issuance costs incurred to refinance Credit Agreement	$ 1,300,000