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v3.20.1

Significant Accounting Policies (Details) |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Apr. 01, 2019 USD ($) | Mar. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2020 USD ($) customer segment | Mar. 31, 2019 USD ($) | Mar. 31, 2018 USD ($) | Apr. 01, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of operating segments | segment |  |  |  |  |  |  |  |  |  | 3 |  |  |
Restricted cash and restricted cash equivalents |  | $ 8,000,000 |  |  |  | $ 0 |  |  |  | $ 8,000,000 | $ 0 | $ 0 |
LIFO inventory (percentage) |  | 60.00% |  |  |  | 62.00% |  |  |  | 60.00% | 62.00% |  |
LIFO reserve |  | $ 444,000,000 |  |  |  | $ 696,000,000 |  |  |  | $ 444,000,000 | $ 696,000,000 |  |
Credits associated with last-in, first-out inventory method |  | 138,000,000 | $ 66,000,000 | $ 33,000,000 | $ 15,000,000 | 146,000,000 | $ 21,000,000 | $ 22,000,000 | $ 21,000,000 | 252,000,000 | 210,000,000 | 99,000,000 |
Shipping and handling costs |  |  |  |  |  |  |  |  |  | 219,028,000,000 | 202,565,000,000 | 197,173,000,000 |
Capitalized software held for internal use, net |  | 400,000,000 |  |  |  | 394,000,000 |  |  |  | 400,000,000 | 394,000,000 |  |
Capitalized software held for internal use, accumulated amortization |  | 1,300,000,000 |  |  |  | $ 1,200,000,000 |  |  |  | 1,300,000,000 | 1,200,000,000 |  |
Sales returns from customers |  |  |  |  |  |  |  |  |  | 3,100,000,000 | 2,900,000,000 | 3,100,000,000 |
Present value of lease liabilities |  | 2,014,000,000 |  |  |  |  |  |  |  | 2,014,000,000 |  |  |
Operating lease ROU assets |  | $ 1,886,000,000 |  |  |  |  |  |  |  | $ 1,886,000,000 |  |  |
Cumulative effect adjustment to opening balance of retained earnings | $ 11,000,000 |  |  |  |  |  |  |  |  |  |  |  | $ 154,000,000
Minimum |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets, useful life |  |  |  |  |  |  |  |  |  | 1 year |  |  |
Maximum |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Property, plant and equipment, useful life |  |  |  |  |  |  |  |  |  | 30 years |  |  |
Intangible assets, useful life |  |  |  |  |  |  |  |  |  | 38 years |  |  |
Capitalized software held for internal use, useful life |  |  |  |  |  |  |  |  |  | 10 years |  |  |
Retained Earnings |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Cumulative effect adjustment to opening balance of retained earnings | 11,000,000 |  |  |  |  |  |  |  |  |  |  |  | $ 154,000,000
Accounting Standards Update 2016-02 |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Present value of lease liabilities | 2,200,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Operating lease ROU assets | 2,100,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Impairment charges | 89,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Accounting Standards Update 2016-02 | Retained Earnings |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Cumulative effect adjustment to opening balance of retained earnings | $ 69,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Shipping and Handling | Selling, Distribution and Administrative Expenses |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Shipping and handling costs |  |  |  |  |  |  |  |  |  | $ 1,000,000,000.0 | $ 951,000,000 | $ 914,000,000 |
Customer Concentration Risk | Sales Revenue, Net |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of largest customers | customer |  |  |  |  |  |  |  |  |  | 10 |  |  |
Percentage of total consolidated revenues (percent) |  |  |  |  |  |  |  |  |  | 51.00% |  |  |
Customer Concentration Risk | Sales Revenue, Net | CVS |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of total consolidated revenues (percent) |  |  |  |  |  |  |  |  |  | 20.00% |  |  |
Customer Concentration Risk | Accounts Receivable |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of total consolidated revenues (percent) |  |  |  |  |  |  |  |  |  | 37.00% |  |  |
Customer Concentration Risk | Accounts Receivable | CVS |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of total consolidated revenues (percent) |  |  |  |  |  |  |  |  |  | 20.00% |  |  |
Product Concentration Risk | Sales Revenue, Net | Distribution and Retail Business |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of total consolidated revenues (percent) |  |  |  |  |  |  |  |  |  | 98.00% |  |  |
Product Concentration Risk | Sales Revenue, Net | Services Business |  |  |  |  |  |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of total consolidated revenues (percent) |  |  |  |  |  |  |  |  |  |  | 2.00% |  |

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