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Pension Benefits - Narrative (Details) | 12 Months Ended
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Mar. 31, 2018 USD ($) $ / shares | Mar. 31, 2017 USD ($) | Mar. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items] |  |  |
Percentage of eligible compensation (up to) | 75.00% |  |
Contribution expenses | $ 82,000,000 | $ 98,000,000 | $ 99,000,000
First Part Of Pay Contribution |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Company match employee contributions (as a percent) | 100.00% |  |
Employee contributions (as a percent) | 3.00% |  |
Second Part Of Pay Contribution |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Company match employee contributions (as a percent) | 50.00% |  |
Employee contributions (as a percent) | 2.00% |  |
Pension Plans, Defined Benefit |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Highest average pay period | 60 months |  |
Plan years prior to freeze date | 15 years |  |
Percentage of obligation | 1.00% |  |
Remediation period if shortfall exceeds threshold amount | 2 years |  |
Unexpected actuarial losses (as a percent) (exceeding) | 10.00% |  |
Expected amortization of actuarial loss | $ (9,000,000) | (14,000,000) |
Expected benefit payments in 2019 | 97,000,000 |  |
Expected benefit payments in 2020 | 184,000,000 |  |
Expected benefit payments in 2021 | 65,000,000 |  |
Expected benefit payments in 2022 | 70,000,000 |  |
Expected benefit payments in 2023 | 67,000,000 |  |
Expected benefit payments in 2024 through 2028 | 339,000,000 |  |
Expected contributions in next fiscal year | $ 55,000,000 |  |
Unit value of cash and cash equivalents (in dollars per share) | $ / shares | $ 1.00 |  |
United States | Pension Plans, Defined Benefit |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Prior service credit | $ 0 | 0 | 0
Actuarial loss | 8,000,000 | 11,000,000 | 44,000,000
Projected benefit obligation | $ 485,000,000 | $ 513,000,000 | 535,000,000
Discount rates | 3.69% | 3.39% |
Increase (decrease) in basis points | 0.0030 |  |
United States | Pension Plans, Defined Benefit | Equity Investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target plan asset allocations (as a percent) | 26.00% | 50.00% |
United States | Pension Plans, Defined Benefit | Fixed Income Investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target plan asset allocations (as a percent) | 70.00% | 45.00% |
United States | Pension Plans, Defined Benefit | Real Estate |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target plan asset allocations (as a percent) | 4.00% | 5.00% |
United States | Unfunded plan | Pension Plans, Defined Benefit |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Projected benefit obligation | $ 160,000,000 | $ 176,000,000 |
Non-U.S. Plans | Pension Plans, Defined Benefit |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Prior service credit | 0 | 2,000,000 | 2,000,000
Actuarial loss | 6,000,000 | 4,000,000 | 5,000,000
Projected benefit obligation | $ 1,035,000,000 | $ 943,000,000 | 899,000,000
Discount rates | 2.35% | 2.35% |
Increase (decrease) in basis points | 0 |  |
Percentage of total plan contribution (exceeding) | 5.00% |  |
Amounts of plan exceeding total plan contribution | $ 16,000,000 | $ 18,000,000 | $ 23,000,000
Funded status (as a percent) | 75.00% |  |
Amounts accrued for liability | $ 0 |  |
Non-U.S. Plans | Unfunded plan | Pension Plans, Defined Benefit |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Projected benefit obligation | 297,000,000 | 276,000,000 |
Norwegian Public Service Pension Fund (SPK) | Non-U.S. Plans | Pension Plans, Defined Benefit |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Amount of plan asset value | $ 38,000,000 | $ 37,000,000 |

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