Employee Benefit Plans - Reconciliation of Benefit Obligations, Plan Assets and Funded Status of Plans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Change in plan assets:
Fair value of plan assets at end of year	$ 331,181	$ 266,734
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	548,641	432,716
Service cost	18,058	14,105	12,741
Interest cost	26,796	25,321	23,860
Participants' contributions
MMA retiree drug subsidy
Actuarial loss	59,910	93,636
Benefits paid	(18,770)	(18,315)
Translation	(3,097)	1,178
Benefit obligation at end of year	631,538	548,641	432,716
Change in plan assets:
Fair value of plan assets at beginning of year	266,734	262,808
Actual return on plan assets	46,174	(4,351)
Employer contribution	37,043	26,592
Participants' contributions
MMA retiree drug subsidy
ERRP subsidy
Benefits paid	(18,770)	(18,315)
Fair value of plan assets at end of year	331,181	266,734	262,808
Funded status at end of year	(300,357)	(281,907)
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	61,835	49,451
Service cost	2,382	2,198	1,711
Interest cost	2,839	3,101	2,943
Participants' contributions	1,632	1,565
MMA retiree drug subsidy	131	200
Actuarial loss	442	9,111
Benefits paid	(3,538)	(3,791)
Translation
Benefit obligation at end of year	65,723	61,835	49,451
Change in plan assets:
Fair value of plan assets at beginning of year
Actual return on plan assets
Employer contribution	1,775	1,524
Participants' contributions	1,632	1,565
MMA retiree drug subsidy	131	200
ERRP subsidy		502
Benefits paid	(3,538)	(3,791)
Fair value of plan assets at end of year
Funded status at end of year	$ (65,723)	$ (61,835)