Stockholders' Equity - Schedule of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	$ 99	$ 53
Reclassified to income statement, net of income tax expense	71	96
Other comprehensive income (loss), net of tax	170	149	$ (198)
Foreign currency translation adjustments, tax	0	0	0
Reclassified to net income, tax	0	0	0
Unrealized gains (losses) on cash flow hedges, tax	6	(12)	(4)
Net actuarial gain (loss) and prior service credit (costs), tax	2	(8)	5
Amortization of actuarial loss, prior service and transition obligation, tax	1	1	0
Foreign currency translation adjustments and other, tax	0	0	0
Foreign Currency Translation Adjustments, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	312	(151)	(431)
Reclassified to income statement, net of income tax expense	47	0	0
Other comprehensive income (loss), net of tax	359	(151)	(431)
Unrealized Gains (Losses) on Net Investment Hedges, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	(175)	85	241
Reclassified to income statement, net of income tax expense	0	0	0
Other comprehensive income (loss), net of tax	(175)	85	241
Unrealized gain (loss) on net investment hedges, tax	62	(30)	(71)
Reclassification to income statement, tax expense	0	0	0
Unrealized gains (losses) on cash flow hedges:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	(36)	86	24
Reclassified to income statement, net of income tax expense	0	0	0
Other comprehensive income (loss), net of tax	(36)	86	24
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	9	27	(51)
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	0	2	9
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	(11)	6	10
Unrealized Net Gains (Losses) and Other Components of Benefit Plans, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassified to income statement, net of income tax expense	24	94	0
Other comprehensive income (loss), net of tax	22	129	(32)
Reclassification to income statement, tax expense	9	33	0
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification to income statement, tax expense	$ 0	$ 0	$ 0