Segment Information (Schedule of Long-Lived Assets by Geographic Area) (Details) - USD ($) $ in Millions	6 Months Ended
	Jul. 31, 2020	Jan. 31, 2020
Revenues From External Customers And Long-Lived Assets [Line Items]
Long-lived assets by geographic area	$ 1,085	$ 1,069
United States
Revenues From External Customers And Long-Lived Assets [Line Items]
Long-lived assets by geographic area	$ 864	860
United States | Assets Benchmark | Geographic Concentration Risk
Revenues From External Customers And Long-Lived Assets [Line Items]
Concentration risk, percentage	80.00%
International
Revenues From External Customers And Long-Lived Assets [Line Items]
Long-lived assets by geographic area	$ 221	$ 209
India | Assets Benchmark | Geographic Concentration Risk
Revenues From External Customers And Long-Lived Assets [Line Items]
Concentration risk, percentage	10.00%