Share Repurchases (Narrative) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	9 Months Ended		0 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Jun. 06, 2013 2011 Share Repurchase Program [Member]	Jun. 06, 2013 2013 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Share Repurchase Program, Authorized Amount			$ 15,000,000,000	$ 15,000,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount			712,000,000
Total Number of Shares Repurchased	77.9	70.9
Average Price Paid per Share	$ 74.54	$ 65.69
Total Share Repurchase	$ 5,806,000,000	$ 4,657,000,000