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Pension Benefits - Summary of Pension Plan Assets Using Fair Value Hierarchy by Asset Class (Details) - Pension Plans, Defined Benefit - USD ($) $ in Millions | Mar. 31, 2021 | Mar. 31, 2020 | Mar. 31, 2019
--- | --- | --- | ---
UNITED STATES |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | $ 0 | $ 0 | $ 322
Non-U.S. Plans |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 735 | 594 | $ 642
Non-U.S. Plans | Investment Assets at Fair Value |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 683 | 552 |
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 162 | 215 |
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 517 | 334 |
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 4 | 3 |
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 5 | 13 |
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 5 | 13 |
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
Non-U.S. Plans | Equity commingled funds | Investment Assets at Fair Value |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 181 | 128 |
Non-U.S. Plans | Equity commingled funds | Investment Assets at Fair Value | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 64 | 53 |
Non-U.S. Plans | Equity commingled funds | Investment Assets at Fair Value | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 117 | 75 |
Non-U.S. Plans | Equity commingled funds | Investment Assets at Fair Value | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
Non-U.S. Plans | Equity commingled funds | Assets held at NAV practical expedient |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 10 | 8 |
Non-U.S. Plans | Government securities | Investment Assets at Fair Value |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 149 | 145 |
Non-U.S. Plans | Government securities | Investment Assets at Fair Value | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 5 | 6 |
Non-U.S. Plans | Government securities | Investment Assets at Fair Value | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 144 | 139 |
Non-U.S. Plans | Government securities | Investment Assets at Fair Value | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 36 | 31 |
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 6 | 14 |
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 30 | 17 |
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
Non-U.S. Plans | Fixed income commingled funds | Investment Assets at Fair Value |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 274 | 208 |
Non-U.S. Plans | Fixed income commingled funds | Investment Assets at Fair Value | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 51 | 107 |
Non-U.S. Plans | Fixed income commingled funds | Investment Assets at Fair Value | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 222 | 101 |
Non-U.S. Plans | Fixed income commingled funds | Investment Assets at Fair Value | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 1 | 0 |
Non-U.S. Plans | Real estate funds and Other | Investment Assets at Fair Value |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 38 | 27 |
Non-U.S. Plans | Real estate funds and Other | Investment Assets at Fair Value | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 31 | 22 |
Non-U.S. Plans | Real estate funds and Other | Investment Assets at Fair Value | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 4 | 2 |
Non-U.S. Plans | Real estate funds and Other | Investment Assets at Fair Value | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 3 | 3 |
Non-U.S. Plans | Real estate funds and Other | Assets held at NAV practical expedient |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | $ 42 | $ 34 |

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