Stockholders' Equity - Stock Options Outstanding (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Oct. 31, 2019
Outstanding Stock Options
Beginning balance (in shares)	26
Options granted under all plans (in shares)	10
Exercised (in shares)	(5)
Canceled (in shares)	(1)
Ending balance (in shares)	30
Outstanding Stock Options, Vested or expected to vest (in shares)	28
Outstanding Stock Options, Exercisable (in shares)	16
Options Outstanding Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 74.15
Options granted under all plans (in dollars per share)	131.92
Exercised (in dollars per share)	57.53
Canceled (in dollars per share)	113.16
Ending balance (in dollars per share)	93.81
Weighted-Average Exercise Price, Vested or expected to vest (in dollars per share)	90.70
Weighted-Average Exercise Price, Exercisable (in dollars per share)	$ 62.63
Aggregate Intrinsic Value
Balance	$ 1,907
Vested or expected to vest	1,866
Exercisable	$ 1,467
Stock Options Outstanding Information
Options, Number Outstanding (in shares)	30
Weighted-Average Remaining Contractual Life, Options Outstanding	4 years 8 months 12 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 93.81
Options Exercisable, Number of Shares (in shares)	16
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 62.63
$0.27 to $52.30
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	0.27
Range of Exercise Prices, Maximum (in dollars per share)	$ 52.30
Options, Number Outstanding (in shares)	6
Weighted-Average Remaining Contractual Life, Options Outstanding	4 years
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 26.34
Options Exercisable, Number of Shares (in shares)	6
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 27.65
$54.36 to $75.57
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	54.36
Range of Exercise Prices, Maximum (in dollars per share)	$ 75.57
Options, Number Outstanding (in shares)	7
Weighted-Average Remaining Contractual Life, Options Outstanding	3 years 3 months 18 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 67.63
Options Exercisable, Number of Shares (in shares)	5
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 65.95
$76.48 to $113.00
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	76.48
Range of Exercise Prices, Maximum (in dollars per share)	$ 113.00
Options, Number Outstanding (in shares)	4
Weighted-Average Remaining Contractual Life, Options Outstanding	3 years 10 months 24 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 83.71
Options Exercisable, Number of Shares (in shares)	3
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 82.13
118.04
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	$ 118.04
Options, Number Outstanding (in shares)	5
Weighted-Average Remaining Contractual Life, Options Outstanding	5 years 3 months 18 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 118.04
Options Exercisable, Number of Shares (in shares)	2
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 118.04
$122.03 to $157.70
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	122.03
Range of Exercise Prices, Maximum (in dollars per share)	$ 157.70
Options, Number Outstanding (in shares)	3
Weighted-Average Remaining Contractual Life, Options Outstanding	6 years 6 months
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 144.03
Options Exercisable, Number of Shares (in shares)	0
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 0.00
161.5
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	$ 161.50
Options, Number Outstanding (in shares)	5
Weighted-Average Remaining Contractual Life, Options Outstanding	6 years 4 months 24 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 161.50
Options Exercisable, Number of Shares (in shares)	0
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 0.00