Stockholders' Equity - Stock Options Outstanding (Detail) (USD $)	9 Months Ended
	Oct. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Number Outstanding	24,494,456
Weighted- Average Remaining Contractual Life (Years), Options Outstanding	3 years 11 months 1 day
Weighted- Average Exercise Price, Options Outstanding	$ 39.11
Options Exercisable, Number of Shares	10,185,611
Options Exercisable, Weighted- Average Exercise Price	$ 31.18
$0.58 to $27.06
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 0.58
Range of Exercise Prices, Maximum	$ 27.06
Options, Number Outstanding	5,368,871
Weighted- Average Remaining Contractual Life (Years), Options Outstanding	3 years 1 month 1 day
Weighted- Average Exercise Price, Options Outstanding	$ 21.39
Options Exercisable, Number of Shares	3,508,231
Options Exercisable, Weighted- Average Exercise Price	$ 20.72
$27.56 to $34.63
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 27.56
Range of Exercise Prices, Maximum	$ 34.63
Options, Number Outstanding	1,004,893
Weighted- Average Remaining Contractual Life (Years), Options Outstanding	3 years 7 months 1 day
Weighted- Average Exercise Price, Options Outstanding	$ 30.86
Options Exercisable, Number of Shares	428,981
Options Exercisable, Weighted- Average Exercise Price	$ 30.54
35.63
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 35.63
Range of Exercise Prices, Maximum	$ 35.63
Options, Number Outstanding	3,530,909
Weighted- Average Remaining Contractual Life (Years), Options Outstanding	1 year 1 month 0 days
Weighted- Average Exercise Price, Options Outstanding	$ 35.63
Options Exercisable, Number of Shares	3,401,222
Options Exercisable, Weighted- Average Exercise Price	$ 35.63
$35.87 to $39.09
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 35.87
Range of Exercise Prices, Maximum	$ 39.09
Options, Number Outstanding	5,736,545
Weighted- Average Remaining Contractual Life (Years), Options Outstanding	2 years 11 months 1 day
Weighted- Average Exercise Price, Options Outstanding	$ 38.12
Options Exercisable, Number of Shares	2,578,871
Options Exercisable, Weighted- Average Exercise Price	$ 38.13
$40.19 to $52.14
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 40.19
Range of Exercise Prices, Maximum	$ 52.14
Options, Number Outstanding	769,316
Weighted- Average Remaining Contractual Life (Years), Options Outstanding	5 years 1 month 1 day
Weighted- Average Exercise Price, Options Outstanding	$ 43.07
Options Exercisable, Number of Shares	200,449
Options Exercisable, Weighted- Average Exercise Price	$ 43.16
$52.30
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 52.30
Range of Exercise Prices, Maximum	$ 52.30
Options, Number Outstanding	5,278,748
Weighted- Average Remaining Contractual Life (Years), Options Outstanding	6 years 1 month 1 day
Weighted- Average Exercise Price, Options Outstanding	$ 52.30
Options Exercisable, Number of Shares	0
Options Exercisable, Weighted- Average Exercise Price	$ 0.00
$53.60 to $63.66
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 53.60
Range of Exercise Prices, Maximum	$ 63.66
Options, Number Outstanding	2,805,174
Weighted- Average Remaining Contractual Life (Years), Options Outstanding	6 years 7 months 1 day
Weighted- Average Exercise Price, Options Outstanding	$ 56.46
Options Exercisable, Number of Shares	67,857
Options Exercisable, Weighted- Average Exercise Price	$ 54.28