New Lease Accounting Standard - Schedule of future minimum payments (Details) - USD ($) $ in Millions	Jul. 28, 2019	Jan. 28, 2019	Jan. 27, 2019
Leases [Abstract]
2020 (excluding first half of fiscal year 2020)	$ 55
2021	109
2022	100
2023	81
2024	57
2025 and thereafter	281
Total	683
Less imputed interest	116
Present value of net future minimum lease payments	567	$ 500
Less short-term operating lease liabilities	84		$ 0
Long-term operating lease liabilities	$ 483		$ 0