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Debt (Textual) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended
	Feb. 25, 2013	Apr. 30, 2013	Apr. 30, 2013 5.0% notes due in fiscal 2014 [Member]	Feb. 25, 2013 5.0% notes due in fiscal 2014 [Member]	Apr. 30, 2012 5.0% notes due in fiscal 2014 [Member]
Debt Instrument [Line Items]
Interest rate on long term debt (percent)			5.00%	5.00%	5.00%
Debt redemption costs	$ 9
Long-term Debt, Fiscal Year Maturity [Abstract]
2014		2
2015		0
2016		250
2017		0
2018		250
After 2018		$ 500