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Number of Largest Customers

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Amount of allowance for credit loss on accounts receivable.

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For each balance sheet presented, the amount of accumulated amortization for capitalized computer software costs.

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Amount of expense for amortization of capitalized computer software costs.

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The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods.

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The change in the inventory reserve representing the cumulative difference in cost between the first in, first out and the last in, first out inventory valuation methods, which change has been reflected in the statement of income during the period.

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Amount of loss from reductions in inventory due to subsequent measurement adjustments, including, but not limited to, physical deterioration, obsolescence, or changes in price levels.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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Significant Accounting Policies (Details) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Significant Accounting Policies (Details) $ in Millions	Sep. 30, 2020 segment	Mar. 31, 2021 USD ($) segment	Mar. 31, 2021 USD ($) customer	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Apr. 01, 2020 USD ($)	Apr. 01, 2019 USD ($)	Mar. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reportable segments \| segment	4	4
Allowance for credit losses		$ 198	$ 198	$ 224
LIFO inventory (percentage)		58.00%	58.00%	60.00%
LIFO reserve		$ 406	$ 406	$ 444
Credits associated with last-in, first-out inventory method			38	252	$ 210
Inventory valuation reserves (excluding LIFO reserves)		263	263	96
Shipping and handling costs			8,849	9,182	8,437
Depreciation			344	335	317
Capitalized software held for internal use, net		513	513	400
Capitalized software held for internal use, accumulated amortization		1,400	1,400	1,300
Capitalized software held for internal use, amortization			117	129	137
Sales returns from customers			3,100	3,100	2,900
Cumulative effect adjustment		(175)	(175)	(5,309)	(8,287)			$ (10,057)
Medical-Surgical Solutions
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventory write-down charges			$ 136
Opening retained earnings adjustments: adoption of new accounting standard
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				13	(11)			(154)
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible assets, useful life			1 year
Minimum \| Building and improvements
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life			15 years
Minimum \| Machinery, equipment, and other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life			3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible assets, useful life			38 years
Capitalized software held for internal use, useful life			10 years
Maximum \| Building and improvements
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life			30 years
Maximum \| Machinery, equipment, and other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life			15 years
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment		$ (8,202)	$ (8,202)	(13,022)	(12,409)			(12,986)
Retained Earnings \| Opening retained earnings adjustments: adoption of new accounting standard
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				13	(11)		$ (69)	$ (154)
Accounting Standards Update 2016-13 \| Retained Earnings \| Opening retained earnings adjustments: adoption of new accounting standard
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment						$ 13
Shipping and Handling
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shipping and handling costs			$ 1,000	$ 1,000	$ 951
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)			21.00%
Customer Concentration Risk \| Accounts Receivable
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of total consolidated revenues (percent)			32.00%
Customer Concentration Risk \| Accounts Receivable \| CVS
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of total consolidated revenues (percent)			19.00%
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%	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%	2.00%