Special Charges and Certain Litigation Charges, Net Special Charges (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 24, 2014	Jan. 25, 2013	Jan. 24, 2014	Jan. 25, 2013
Special Charges [Abstract]
Special Charges	$ 0	$ 0	$ 40	$ 0