Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2015	Apr. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - Beginning of Period	$ (7,168)	$ (2,712)
Other Comprehensive Income (Loss) Before Reclassifications	(1,434)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	7
Balances - End of Period	(8,595)	(2,712)
Currency Translation And Other [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - Beginning of Period	(7,011)
Other Comprehensive Income (Loss) Before Reclassifications	(1,553)
Balances - End of Period	(8,564)
Net Investment Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - Beginning of Period	656
Other Comprehensive Income (Loss) Before Reclassifications	(64)
Balances - End of Period	592
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - Beginning of Period	(134)
Other Comprehensive Income (Loss) Before Reclassifications	110
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	10
Balances - End of Period	(14)
Minimum Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - Beginning of Period	(679)
Other Comprehensive Income (Loss) Before Reclassifications	73
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(3)
Balances - End of Period	$ (609)