Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Millions		Jan. 27, 2019	Jan. 28, 2018
Assets
Cash equivalents and marketable securities		$ 7,324	$ 6,895
Level 1 | Money market funds
Assets
Cash equivalents and marketable securities		483	3,789
Level 2
Liabilities
1.00% Convertible Senior Notes	[1]	0	189
Level 2 | 2.20% Notes Due 2021
Liabilities
Long-term debt	[1]	978	982
Level 2 | 3.20% Notes Due 2026
Liabilities
Long-term debt	[1]	961	986
Level 2 | Corporate debt securities
Assets
Cash equivalents and marketable securities		2,620	1,295
Level 2 | Debt securities of United States government agencies
Assets
Cash equivalents and marketable securities		2,280	815
Level 2 | Debt securities issued by the United States Treasury
Assets
Cash equivalents and marketable securities		1,492	573
Level 2 | Foreign government bonds
Assets
Cash equivalents and marketable securities		209	41
Level 2 | Asset-backed securities
Assets
Cash equivalents and marketable securities		151	252
Level 2 | Mortgage-backed securities issued by United States government-sponsored enterprises
Assets
Cash equivalents and marketable securities		$ 89	$ 130

[1] These liabilities are carried on our Consolidated Balance Sheets at their original issuance value, net of unamortized debt discount and issuance costs, and are not marked to fair value each period. Refer to Note 11 of these Notes to the Consolidated Financial Statements for additional information.