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Pension Benefits - Narrative (Details) |  | 12 Months Ended
--- | --- | ---
Dec. 31, 1996 | Mar. 31, 2017 USD ($) $ / shares | Mar. 31, 2016 USD ($) | Mar. 31, 2015 USD ($)
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expected amortization of actuarial loss |  | $ 11,000,000 |  |
Actuarial loss |  | 15,000,000 |  |
Expected benefit payments in 2018 |  | 73,000,000 |  |
Expected benefit payments in 2019 |  | 206,000,000 |  |
Expected benefit payments in 2020 |  | 61,000,000 |  |
Expected benefit payments in 2021 |  | 62,000,000 |  |
Expected benefit payments in 2022 |  | 64,000,000 |  |
Expected benefit payments in 2023 through 2027 |  | 307,000,000 |  |
Expected contributions in next fiscal year |  | $ 30,000,000 |  |
U.S. Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Percentage of eligible compensation (up to) |  | 75.00% |  |
Contribution expenses |  | $ 98,000,000 | $ 99,000,000 | $ 103,000,000
U.S. Plans | 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% |  |
U.S. Plans | 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% |  |
Pensjonsordningen for Apoteketaten (POA) |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Percentage of total plan contribution (exceeding) |  | 5.00% |  |
Amounts of plan exceeding total plan contribution |  | $ 18,000,000 | 23,000,000 | 24,000,000
Funded status (as a percent) |  | 75.00% |  |
Amounts accrued for liability |  | $ 0 |  |
U.S. Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Highest average pay period | 60 months |  |  |
Plan years prior to freeze date | 15 years |  |  |
Unexpected actuarial losses (as a percent) (exceeding) |  | 10.00% |  |
Prior service credit |  | $ 0 | 0 | 8,000,000
Actuarial loss |  | 11,000,000 | 44,000,000 | 27,000,000
Projected benefit obligation |  | $ 513,000,000 | $ 535,000,000 | 583,000,000
Discount rates |  | 3.39% | 3.27% |
Increase (decrease) in basis points |  | 0.0012 |  |
U.S. Plans | Equity Investments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target plan asset allocations (as a percent) |  | 50.00% | 50.00% |
U.S. Plans | Fixed Income Investments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target plan asset allocations (as a percent) |  | 45.00% | 45.00% |
U.S. Plans | Real Estate |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target plan asset allocations (as a percent) |  | 5.00% | 5.00% |
U.S. Plans | Unfunded plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Projected benefit obligation |  | $ 176,000,000 | $ 175,000,000 |
Pension Plans, Defined Benefit |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Unit value of cash and cash equivalents (in dollars per share) | $ / shares |  | $ 1.00 |  |
Non-U.S. Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Percentage of obligation |  | 1.00% |  |
Remediation period if shortfall exceeds threshold amount |  | 2 years |  |
Prior service credit |  | $ 2,000,000 | 2,000,000 | 2,000,000
Actuarial loss |  | 4,000,000 | 5,000,000 | 5,000,000
Projected benefit obligation |  | $ 943,000,000 | $ 899,000,000 | $ 963,000,000
Discount rates |  | 2.35% | 2.84% |
Increase (decrease) in basis points |  | (0.0049) |  |
Amount of plan asset value |  | $ 37,000,000 | $ 40,000,000 |
Non-U.S. Plans | Unfunded plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Projected benefit obligation |  | $ 276,000,000 | $ 272,000,000 |

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- Definition 1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Projected Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6522206 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Accumulated Postretirement Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6503904 + Details
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