Schedule of Notes Payable and Long-Term Debt (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013
Debt Instrument [Line Items]
Total notes payable and long-term debt	$ 1,333	$ 1,295
Less current portion	2	0
Total notes payable and long-term debt, net of current portion	1,331	1,295
Fair value of notes payable and long-term debt	1,350	1,390
Notes Which Mature In December 2020
Debt Instrument [Line Items]
Senior unsecured notes	449	449
Stated interest rate	4.45%
Effective interest rate	4.53%
Notes Which Mature In December 2040
Debt Instrument [Line Items]
Senior unsecured notes	300	300
Stated interest rate	5.95%
Effective interest rate	6.03%
Notes Which Mature In July 2032
Debt Instrument [Line Items]
Senior unsecured notes	248	248
Stated interest rate	7.13%
Effective interest rate	7.43%
Notes Which Mature In July 2033
Debt Instrument [Line Items]
Senior unsecured notes	296	296
Stated interest rate	5.50%
Effective interest rate	5.78%
Other Notes Payable Due On Various Dates Through Fiscal 2021
Debt Instrument [Line Items]
Other notes payable due on various dates through fiscal 2021	$ 40	$ 2
Minimum stated interest rate	0.00%
Maximum stated interest rate	3.70%