Balance Sheet Details (Property And Equipment, Net Schedule) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Property and Equipment, Net [Line Items]
Property and equipment, gross	$ 1,473		$ 1,473		$ 1,391
Less: accumulated depreciation	(1,015)		(1,015)		(942)
Property and equipment, net	458		458		449	[1]
Depreciation expense	32	$ 30	63	$ 60
Computer, equipment and software
Property and Equipment, Net [Line Items]
Property and equipment, gross	795		795		722
Buildings
Property and Equipment, Net [Line Items]
Property and equipment, gross	351		351		340
Leasehold improvements
Property and Equipment, Net [Line Items]
Property and equipment, gross	168		168		161
Equipment, furniture and fixtures, and other
Property and Equipment, Net [Line Items]
Property and equipment, gross	87		87		83
Land
Property and Equipment, Net [Line Items]
Property and equipment, gross	66		66		65
Construction in progress
Property and Equipment, Net [Line Items]
Property and equipment, gross	$ 6		$ 6		$ 20

[1] Derived from audited Consolidated Financial Statements.