Share Repurchases (Schedule Of Company's Share Repurchases) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Equity, Class of Treasury Stock [Line Items]
Total number of shares repurchased	40.7	3.5
Average price paid per share	$ 67.23	$ 80.74
Total amount paid for share repurchases	$ 2,735	$ 280