Employee Benefit Plans - Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost (Detail)	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	7.50%	7.50%	7.50%
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.00%	6.00%	6.50%
Rate of increase in compensation	2.75%	3.50%	3.75%
Excess Plan/SRIP [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.00%	6.00%	6.75%
Japan Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	1.50%	1.75%	3.00%
Rate of increase in compensation	1.00%	1.25%	2.50%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.25%	6.25%	6.75%
Excess Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of increase in compensation	4.25%	5.00%	5.25%
SRIP [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of increase in compensation	7.25%	8.00%	8.25%