Lease and Other Commitments - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Capital Leases
Fiscal 2020	$ 200
Fiscal 2021	0
Fiscal 2022	0
Fiscal 2023	0
Fiscal 2024	0
Thereafter	0
Total minimum lease payments	200
Less: amount representing interest	(9)
Present value of capital lease obligations	191
Operating Leases
Fiscal 2020	778
Fiscal 2021	658
Fiscal 2022	466
Fiscal 2023	369
Fiscal 2024	314
Thereafter	1,610
Total minimum lease payments	4,195
Financing Obligation - Leased Facility
Fiscal 2020	22
Fiscal 2021	23
Fiscal 2022	23
Fiscal 2023	24
Fiscal 2024	24
Thereafter	163
Total minimum lease payments	279
Sublease income, next five years	146
Sublease income, thereafter	79
Financing obligation leased facility	279
Rent expense	365	$ 285
Financing Obligation Leased Facility
Financing Obligation - Leased Facility
Total minimum lease payments	215
Financing obligation leased facility	$ 215