Stockholders' Equity - Schedule of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	$ 53	$ (207)
Amounts reclassified to earnings and other	96	9
Other Comprehensive Income (Loss), Net of Tax	149	(198)	$ 609
Foreign Currency Translation Adjustments, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	(151)	(431)	804
Amounts reclassified to earnings and other	0	0	0
Other Comprehensive Income (Loss), Net of Tax	(151)	(431)	804
Reclassification, tax expense	0	0	0
Tax expense (benefit)	0	0	0
Unrealized Gains (Losses) on Net Investment Hedges, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	85	241	(180)
Amounts reclassified to earnings and other	0	0	0
Other Comprehensive Income (Loss), Net of Tax	85	241	(180)
Reclassification, tax expense	0	0	0
Tax expense (benefit)	(30)	(71)	95
Unrealized Gains (Losses) on Cash Flow Hedges, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	86	24	(30)
Amounts reclassified to earnings and other	0	0	0
Other Comprehensive Income (Loss), Net of Tax	86	24	(30)
Reclassification, tax expense	0	0	0
Tax expense (benefit)	(12)	(4)	9
Net actuarial gain (loss) and prior service credit (cost) arising during the period, net of income tax (expense) benefit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	27	(51)	25
Tax expense (benefit)	(8)	5	(2)
Amortization of actuarial gain, prior service cost and transition obligation, net of income tax (expense)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	2	9	5
Tax expense (benefit)	1	0	(2)
Changes in Retirement-Related Benefit Plans, Foreign Currency Translation Adjustments and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	6	10	(15)
Tax expense (benefit)	0	0	0
Unrealized Net Gains (Losses) and Other Components of Benefit Plans, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified to earnings and other	94	0	0
Other Comprehensive Income (Loss), Net of Tax	129	(32)	15
Reclassification, tax expense	$ (33)	$ 0	$ 0