Summary of Significant Accounting Policies (Details) $ / shares in Units, client in Thousands, $ in Millions	12 Months Ended
	Mar. 31, 2019 USD ($) client country $ / shares	Apr. 01, 2019 USD ($)	Apr. 01, 2018 USD ($)	Mar. 31, 2018 USD ($) $ / shares	Apr. 01, 2017 $ / shares
Retained Earnings Adjustments [Line Items]
Number of clients served | client	6
Number of countries in which entity operates | country	70
Common stock, par value (in dollars per share) | $ / shares	$ 0.01			$ 0.01	$ 0.01
Amortization period	5 years
Adjustment to retained earnings	$ 478			$ 1,301
Income taxes payable	208			127
Deferred revenue and advance contract payments	1,630			1,641
Restricted cash				$ 68
As Previously Reported
Retained Earnings Adjustments [Line Items]
Common stock, par value (in dollars per share) | $ / shares					$ 1.00
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Retained Earnings Adjustments [Line Items]
Adjustment to retained earnings	177		$ 114
Accrued sales commission			158
Income taxes payable	2		(40)
Deferred revenue and advance contract payments	$ (87)		(381)
Other assets			$ (385)
Forecast | Minimum | Accounting Standards Update 2016-02
Retained Earnings Adjustments [Line Items]
Right-of-use asset		$ 1,600
Operating lease liability		1,600
Forecast | Maximum | Accounting Standards Update 2016-02
Retained Earnings Adjustments [Line Items]
Right-of-use asset		1,800
Operating lease liability		$ 1,800