Schedule Of Share-based Compensation Options Activity (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation arrangement by share based payment award options expiration term	8
Number of Shares
Options outstanding at January 31, 2011	30.4
Granted	5.4
Exercised	(5.3)
Cancelled	(2.1)
Options outstanding at January 31, 2012	28.4
Options exercisable at January 31, 2012	16.7
Options vested and exercisable as of January 31, 2012	27.7	[1]
Options available for grant at January 31, 2012	18.0
Weighted average price per share
Options outstanding at January 31, 2011	$ 28.93
Granted	$ 40.71
Exercised	$ 24.85
Cancelled	$ 36.29
Options outstanding at January 31, 2012	$ 31.39
Options exercisable at January 31, 2012	$ 30.98
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 31.25	[1]
Outside directors stock plan 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation arrangement by share based payment award options expiration term	7
Maximum | Employee Stock Plan 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation arrangement by share based payment award options expiration term	10

[1] Options expected to vest reflect an estimated forfeiture rate. The weighted average remaining contractual life for these options is 3.9 years and the aggregate intrinsic value is $199.3 million.