Balance Sheet Details (Property And Equipment, Net Schedule) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Mar. 31, 2017
Property and Equipment, Net [Line Items]
Property and equipment, gross	$ 1,351	$ 1,315
Less: accumulated depreciation	(904)	(881)
Property and equipment, net	447	434	[1]
Computer, equipment and software
Property and Equipment, Net [Line Items]
Property and equipment, gross	724	723
Buildings
Property and Equipment, Net [Line Items]
Property and equipment, gross	336	316
Leasehold improvements
Property and Equipment, Net [Line Items]
Property and equipment, gross	137	126
Equipment, furniture and fixtures, and other
Property and Equipment, Net [Line Items]
Property and equipment, gross	81	82
Land
Property and Equipment, Net [Line Items]
Property and equipment, gross	66	61
Construction in progress
Property and Equipment, Net [Line Items]
Property and equipment, gross	$ 7	$ 7

[1] Derived from audited Consolidated Financial Statements.