Accumulated Other Comprehensive Income (Loss) (Details) $ in Millions	9 Months Ended
	Oct. 31, 2015 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - beginning of period	$ (7,168)
Other comprehensive income (loss) before reclassifications	(3,512)
Amounts reclassified from accumulated other comprehensive income (loss)	21
Balances - end of period	(10,659)
Currency translation and other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - beginning of period	(7,011)
Other comprehensive income (loss) before reclassifications	(3,590)
Balances - end of period	(10,601)
Net investment hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - beginning of period	656
Other comprehensive income (loss) before reclassifications	101
Balances - end of period	757
Cash flow hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - beginning of period	(134)
Other comprehensive income (loss) before reclassifications	(104)
Amounts reclassified from accumulated other comprehensive income (loss)	29
Balances - end of period	(209)
Minimum pension liability
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances - beginning of period	(679)
Other comprehensive income (loss) before reclassifications	81
Amounts reclassified from accumulated other comprehensive income (loss)	(8)
Balances - end of period	$ (606)