Employee and Director Stock Plans - Options Outstanding and Exercisable (Detail) shares in Millions	Jan. 31, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Vested and Exercisable, Number of Shares | shares	0.6
Options Vested and Exercisable, Weighted average exercise price (in dollars per share)	$ 39.25
$27.40 - $38.55
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of per-share exercise prices, Lower Limit	27.40
Range of per-share exercise prices, Upper Limit	$ 38.55
Options Vested and Exercisable, Number of Shares | shares	0.2
Options Vested and Exercisable, Weighted average exercise price (in dollars per share)	$ 33.00
$38.56 - $42.38
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of per-share exercise prices, Lower Limit	38.56
Range of per-share exercise prices, Upper Limit	$ 42.38
Options Vested and Exercisable, Number of Shares | shares	0.3
Options Vested and Exercisable, Weighted average exercise price (in dollars per share)	$ 41.62
$42.39 - $43.81
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of per-share exercise prices, Lower Limit	42.39
Range of per-share exercise prices, Upper Limit	$ 43.81
Options Vested and Exercisable, Number of Shares | shares	0.1
Options Vested and Exercisable, Weighted average exercise price (in dollars per share)	$ 43.81