Balance Sheet Details (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2020	[1]
Remaining Performance Obligations
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months		12 months
Depreciation expense	$ 37	$ 29	$ 100	$ 89
Deferred Revenue, Current	1,380		1,380		$ 945
Deferred Revenue, Revenue Recognized			1,002	$ 1,169
Unsatisfied Performance Obligations [Member]
Remaining Performance Obligations
Revenue, Remaining Performance Obligation, Amount	$ 33		$ 33

[1] Derived from audited Consolidated Financial Statements.