Accumulated Other Comprehensive Income (Loss) (Details) (USD $)	3 Months Ended		9 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011 Currency Translation And Other [Member]	Oct. 31, 2011 Derivative Instruments [Member]	Oct. 31, 2011 Minimum Pension Liability [Member]	Jan. 31, 2011 Minimum Pension Liability [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balances - February 1, 2011			$ 646,000,000		$ 1,226,000,000	$ 60,000,000	$ (640,000,000)	$ (640,000,000)
Currency translation adjustment			(1,923,000,000)		(1,923,000,000)
Net change in fair value of derivatives	15,000,000	(81,000,000)	(98,000,000)	(106,000,000)		(98,000,000)
Balances - October 31, 2011	(1,375,000,000)	105,000,000	(1,375,000,000)	105,000,000	(697,000,000)	(38,000,000)	(640,000,000)	(640,000,000)
Net translation loss related to net investment hedges	1,200,000,000		1,200,000,000
Accumulated comprehensive income (loss) to earnings from remeasurements of non U.S-denominated debt	$ (24,000,000)		$ (24,000,000)