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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

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- Definition Amount of tax expense (benefit), before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 10 -Section 45 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=120253306&loc=d3e28129-110885 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 45 -Paragraph 21 -URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32262-110900 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e640-108580 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30755-110894 + Details
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