Stockholders' Equity - Stock Options Outstanding (Detail) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended
	Jul. 31, 2020 USD ($) $ / shares shares
Outstanding Stock Options
Beginning balance (in shares) | shares	27
Options granted under all plans (in shares) | shares	8
Exercised (in shares) | shares	(6)
Plan shares expired or canceled (in shares) | shares	(1)
Ending balance (in shares) | shares	28
Outstanding Stock Options, Vested or expected to vest (in shares) | shares	25
Outstanding Stock Options, Exercisable (in shares) | shares	11
Options Outstanding Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 98.56
Options granted under all plans (in dollars per share)	143.56
Exercised (in dollars per share)	75.67
Plan shares expired or canceled (in dollars per share)	136.90
Ending balance (in dollars per share)	115.05
Weighted-Average Exercise Price, Vested or expected to vest (in dollars per share)	112.45
Weighted-Average Exercise Price, Exercisable (in dollars per share)	$ 79.70
Aggregate Intrinsic Value
Balance | $	$ 2,183
Vested or expected to vest | $	2,073
Exercisable | $	$ 1,312
Stock Options Outstanding Information
Options, Number Outstanding (in shares) | shares	28
Weighted-Average Remaining Contractual Life, Options Outstanding	5 years
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 115.05
Options Exercisable, Number of Shares (in shares) | shares	11
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 79.70
$0.36 to $59.34
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	0.36
Range of Exercise Prices, Maximum (in dollars per share)	$ 59.34
Options, Number Outstanding (in shares) | shares	6
Weighted-Average Remaining Contractual Life, Options Outstanding	3 years 6 months
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 39.57
Options Exercisable, Number of Shares (in shares) | shares	5
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 40.99
$59.64 to $80.99
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	59.64
Range of Exercise Prices, Maximum (in dollars per share)	$ 80.99
Options, Number Outstanding (in shares) | shares	4
Weighted-Average Remaining Contractual Life, Options Outstanding	3 years 4 months 24 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 76.55
Options Exercisable, Number of Shares (in shares) | shares	3
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 77.67
$81.88 to $118.04
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	81.88
Range of Exercise Prices, Maximum (in dollars per share)	$ 118.04
Options, Number Outstanding (in shares) | shares	4
Weighted-Average Remaining Contractual Life, Options Outstanding	4 years 6 months
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 114.83
Options Exercisable, Number of Shares (in shares) | shares	2
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 113.95
$122.03 to $148.95
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	122.03
Range of Exercise Prices, Maximum (in dollars per share)	$ 148.95
Options, Number Outstanding (in shares) | shares	2
Weighted-Average Remaining Contractual Life, Options Outstanding	5 years 9 months 18 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 142.35
Options Exercisable, Number of Shares (in shares) | shares	0
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 0.00
$154.14
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	154.14
Range of Exercise Prices, Maximum (in dollars per share)	$ 154.14
Options, Number Outstanding (in shares) | shares	6
Weighted-Average Remaining Contractual Life, Options Outstanding	6 years 8 months 12 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 154.14
Options Exercisable, Number of Shares (in shares) | shares	0
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 0.00
$155.20 to $191.65
Stock Options Outstanding Information
Range of Exercise Prices, Minimum (in dollars per share)	155.20
Range of Exercise Prices, Maximum (in dollars per share)	$ 191.65
Options, Number Outstanding (in shares) | shares	6
Weighted-Average Remaining Contractual Life, Options Outstanding	5 years 8 months 12 days
Weighted-Average Exercise Price, Options Outstanding (in dollars per share)	$ 163.49
Options Exercisable, Number of Shares (in shares) | shares	1
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 161.50