Fair Value Measurements - Schedule of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jul. 31, 2021	Jan. 31, 2021
Financial Assets:
Marketable securities	$ 3,174,029	$ 2,004,410
Commercial paper
Financial Assets:
Marketable securities	33,729	26,222
Agency bonds
Financial Assets:
Marketable securities	491,997	461,365
Corporate and other debt securities
Financial Assets:
Marketable securities	380,598	466,256
U.S. government agency securities
Financial Assets:
Marketable securities	2,213,712	834,665
Fair Value, Recurring Basis
Financial Assets:
Cash equivalents	1,013,181	1,576,855
Marketable securities	3,174,029	2,004,410
Total financial assets	4,310,514	3,588,733
Fair Value, Recurring Basis | Commercial paper
Financial Assets:
Marketable securities	33,729	26,222
Fair Value, Recurring Basis | Agency bonds
Financial Assets:
Marketable securities	491,997	461,365
Fair Value, Recurring Basis | Corporate and other debt securities
Financial Assets:
Marketable securities	380,598	466,256
Fair Value, Recurring Basis | U.S. government agency securities
Financial Assets:
Marketable securities	2,213,712	834,665
Fair Value, Recurring Basis | Treasury bills
Financial Assets:
Marketable securities	53,993	215,902
Fair Value, Recurring Basis | Certificates of deposit
Financial Assets:
Certificate of deposit included in prepaid expenses and other current assets		100
Certificates of deposit included in other assets, noncurrent	797	2,238
Fair Value, Recurring Basis | Publicly held equity securities included in strategic investments
Financial Assets:
Publicly held equity securities included in strategic investments	107,076
Privately held debt securities included in strategic investments		5,130
Fair Value, Recurring Basis | Privately held debt securities included in strategic investments
Financial Assets:
Privately held debt securities included in strategic investments	15,431
Fair Value, Recurring Basis | Money market funds
Financial Assets:
Cash equivalents	688,073	958,357
Fair Value, Recurring Basis | Treasury bills
Financial Assets:
Cash equivalents	325,108	618,498
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1
Financial Assets:
Cash equivalents	688,073	958,357
Marketable securities	0	0
Total financial assets	795,149	958,357
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Commercial paper
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Agency bonds
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Corporate and other debt securities
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | U.S. government agency securities
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Treasury bills
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Certificates of deposit
Financial Assets:
Certificate of deposit included in prepaid expenses and other current assets		0
Certificates of deposit included in other assets, noncurrent	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Publicly held equity securities included in strategic investments
Financial Assets:
Publicly held equity securities included in strategic investments	107,076
Privately held debt securities included in strategic investments		0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Privately held debt securities included in strategic investments
Financial Assets:
Privately held debt securities included in strategic investments	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Money market funds
Financial Assets:
Cash equivalents	688,073	958,357
Fair Value, Recurring Basis | Fair Value, Inputs, Level 1 | Treasury bills
Financial Assets:
Cash equivalents	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2
Financial Assets:
Cash equivalents	325,108	618,498
Marketable securities	3,174,029	2,004,410
Total financial assets	3,499,934	2,625,246
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Commercial paper
Financial Assets:
Marketable securities	33,729	26,222
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Agency bonds
Financial Assets:
Marketable securities	491,997	461,365
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Corporate and other debt securities
Financial Assets:
Marketable securities	380,598	466,256
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | U.S. government agency securities
Financial Assets:
Marketable securities	2,213,712	834,665
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Treasury bills
Financial Assets:
Marketable securities	53,993	215,902
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Certificates of deposit
Financial Assets:
Certificate of deposit included in prepaid expenses and other current assets		100
Certificates of deposit included in other assets, noncurrent	797	2,238
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Publicly held equity securities included in strategic investments
Financial Assets:
Privately held debt securities included in strategic investments		0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Privately held debt securities included in strategic investments
Financial Assets:
Privately held debt securities included in strategic investments	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Money market funds
Financial Assets:
Cash equivalents	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 2 | Treasury bills
Financial Assets:
Cash equivalents	325,108	618,498
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3
Financial Assets:
Cash equivalents	0	0
Marketable securities	0	0
Total financial assets	15,431	5,130
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Commercial paper
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Agency bonds
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Corporate and other debt securities
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | U.S. government agency securities
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Treasury bills
Financial Assets:
Marketable securities	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Certificates of deposit
Financial Assets:
Certificate of deposit included in prepaid expenses and other current assets		0
Certificates of deposit included in other assets, noncurrent	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Publicly held equity securities included in strategic investments
Financial Assets:
Privately held debt securities included in strategic investments		5,130
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Privately held debt securities included in strategic investments
Financial Assets:
Privately held debt securities included in strategic investments	15,431
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Money market funds
Financial Assets:
Cash equivalents	0	0
Fair Value, Recurring Basis | Fair Value, Inputs, Level 3 | Treasury bills
Financial Assets:
Cash equivalents	$ 0	$ 0