Employee Benefit Plans - Weighted-Average Assumptions Used to Determine Benefit Obligations (Detail)	Jan. 31, 2013	Jan. 31, 2012
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.50%	5.00%
Rate of increase in compensation	2.75%	2.75%
Excess Plan/SRIP [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.50%	5.00%
Japan Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	1.25%	1.50%
Rate of increase in compensation	1.00%	1.00%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.50%	5.25%
Excess Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of increase in compensation	4.25%	4.25%
SRIP [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of increase in compensation	7.25%	7.25%