Cash, Cash Equivalents and Investments - Summary of Contractual Maturity (Details) $ in Millions	Jan. 31, 2021 USD ($)
Contractual maturities of investments
Due in one year or less, Cost	$ 390
Due after one through five years, Cost	857
No single maturity date, Cost	683
Cost of short-term and long-term investments	1,930
Due in one year or less, Estimated Fair Value	392
Due after one through five years, Estimated Fair Value	869
No single maturity date, Estimated Fair Value	750
Estimated fair value of short-term and long-term investments	$ 2,011