McKesson (MCK) 10-K 12 May 15 2015 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Mar. 31, 2015	Apr. 30, 2015	Sep. 30, 2014
Document And Entity Information [Abstract]
Entity Registrant Name	McKESSON CORPORATION
Entity Central Index Key	927653
Entity Tax Identification Number	943207296
Document Type	10-K
Current Fiscal Year End Date	-28
Document Period End Date	31-Mar-15
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2015
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Amendment Flag	FALSE
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$45
Entity Common Stock, Shares Outstanding		231,553,531

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Income Statement [Abstract]
Revenues	$179,045	[1]	$137,392	[1]	$122,196	[1]
Cost of Sales	-167,634		-129,040		-115,315
Gross Profit	11,411		8,352		6,881
Operating Expenses
Selling, distribution and administrative expenses	-7,901		-5,388		-4,110
Research and development	-392		-457		-433
Claims and litigation charges	-150		-68		-72
Gain on business combination	0		0		81
Total Operating Expenses	-8,443		-5,913		-4,534
Operating Income	2,968		2,439		2,347
Other Income, Net	63		32		34
Impairment of an Equity Investment	0		0		-191
Interest Expense	-374		-300		-240
Total income from continuing operations before income taxes	2,657		2,171		1,950
Income Tax Expense	-815		-757		-587
Income from continuing operations	1,842		1,414		1,363
Income (Loss) from Discontinued Operations, Net of Tax	-299		-156		-25
Net Income	1,543		1,258		1,338
Net loss attributable to noncontrolling interests	-67		5		0
Net Income Attributable to McKesson	$1,476		$1,263		$1,338
Diluted
Continuing operations	$7.54	[2]	$6.08	[2]	$5.69	[2]
Discontinued operations	($1.27)	[2]	($0.67)	[2]	($0.10)	[2]
Total	$6.27	[2]	$5.41	[2]	$5.59	[2]
Basic
Continuing operations	$7.66	[2]	$6.19	[2]	$5.81	[2]
Discontinued operations	($1.29)	[2]	($0.68)	[2]	($0.10)	[2]
Total	$6.37	[2]	$5.51	[2]	$5.71	[2]
Weighted Average Common Shares
Diluted	235		233		239
Basic	232		229		235
[1]	Net revenues were attributed to geographic areas based on the customers’ shipment locations.
[2]	Certain computations may reflect rounding adjustments.

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net Income	$1,543	$1,258	$1,338
Other Comprehensive Income (Loss), Net of Tax
Foreign currency translation adjustments arising during the period	-1,855	53	-52
Unrealized losses on cash flow hedges arising during the period	-10	-6	0
Unrealized losses on cash flow hedges arising during period, net of income tax benefit of nil, nil and nil	-13	-6	0
Retirement-related benefit plans	-124	36	-18
Other Comprehensive Income (Loss), Net of Tax	-1,989	83	-70
Comprehensive Income	-446	1,341	1,268
Comprehensive Income Attributable to Noncontrolling Interests	212	-16	0
Comprehensive Income Attributable to McKesson	($234)	$1,325	$1,268

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Mar. 31, 2014
In Millions, unless otherwise specified
Current Assets
Cash and cash equivalents	$5,341	$4,193
Receivables, net	15,914	13,780
Inventories, net	14,296	12,986
Prepaid expenses and other	1,119	1,877
Total Current Assets	36,670	32,836
Property, Plant and Equipment, Net	2,045	2,196
Goodwill, beginning balance	9,817	9,927
Intangible Assets, Net	3,441	4,871
Other Assets	1,897	1,929
Total Assets	53,870	51,759
Current Liabilities
Drafts and accounts payable	25,166	21,128
Short-term borrowings	135	248
Deferred revenue	1,078	1,236
Deferred tax liabilities	1,820	1,588
Current portion of long-term debt	1,529	1,417
Other accrued liabilities	3,769	3,998
Total Current Liabilities	33,497	29,615
Long-Term Debt	8,180	8,929
Other Noncurrent Liabilities	2,722	2,897
Other Commitments and Contingent Liabilities
Redeemable Noncontrolling Interests	1,386	0
Stockholders' Equity
Preferred stock, $0.01 par value, 100 shares authorized, no shares issued or outstanding	0	0
Common stock, $0.01 par value, 800 shares authorized at March 31, 2015 and 2014, 384 and 381 shares issued at March 31, 2015 and 2014	4	4
Additional Paid-in Capital	6,968	6,552
Retained Earnings	12,705	11,453
Accumulated Other Comprehensive Income (Loss)	-1,713	-3
Other	-7	23
Treasury Shares, at Cost, 152 and 150 at March 31, 2015 and 2014	-9,956	-9,507
Total McKesson Stockholders' Equity	8,001	8,522
Noncontrolling Interests	84	1,796
Total Equity	8,085	10,318
Total Liabilities and Stockholders' Equity	$53,870	$51,759

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Mar. 31, 2014
Stockholders' Equity
Preferred stock, par value	$0.01	$0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	384,000,000	381,000,000
Treasury stock, shares	152,000,000	150,000,000

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total		Common Stock [Member]	Additional Paid-in Capital [Member]	Other Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]	Celesio [Member]
In Millions
Beginning Balance, Total Equity at Mar. 31, 2012	$6,831		$4	$5,571	$4	$9,451	$5	($8,204)	$0
Beginning Balance, McKesson Stockholders' Equity, Shares at Mar. 31, 2012			373
Beginning Balance, McKesson Stockholders' Equity, Treasury Stock, Shares at Mar. 31, 2012								-138
Issuance of shares under employee plans	111		0	166				-55
Issuance of shares under employee plans, shares			5					0
Share-based compensation	167			167
Tax benefit related to issuance of shares under employee plans	34			34
Conversion of Celesio convertible bonds	0
Other comprehensive income (loss)							-70
Other Comprehensive Income (Loss), Net of Tax	-70
Net Income Attributable to McKesson	1,338
Net income (loss) attributable to noncontrolling interests	0
Net Income	1,338
Repurchase of common stock	-1,159	[1]		162				-1,321
Stock Repurchased and Retired During Period, Shares			-2					2
Treasury Stock, Retired, Cost Method, Amount	195		0	-22		-195		217
Treasury Stock Acquired, Net of Retirements, Amount	0
Repurchase of common stock, Shares	-13	[1],[2],[3]						-13
Cash dividends declared: $0.96 for 2015, $0.92 for 2014 and $0.80 for 2013 per common share	-192					-192
Other	10				10
Ending Balance, Total Equity at Mar. 31, 2013	7,070		4	6,078	14	10,402	-65	-9,363	0
Ending Balance, McKesson Stockholders' Equity, Shares at Mar. 31, 2013			376
Ending Balance, McKesson Stockholders' Equity, Treasury Stock, Shares at Mar. 31, 2013								-149
Issuance of shares under employee plans	47		0	177				-130
Issuance of shares under employee plans, shares			5					-1
Share-based compensation	160			160
Tax benefit related to issuance of shares under employee plans	92			92
Noncontrolling interests									1,500
Noncontrolling Interest, Increase from Business Combination	1,500
Conversion of Celesio convertible bonds	313			33					280
Other comprehensive income (loss)							62		21
Other Comprehensive Income (Loss), Net of Tax	83
Net Income Attributable to McKesson	1,263					1,263
Net income (loss) attributable to noncontrolling interests	-5								-5
Net Income	1,258
Repurchase of common stock	0			14				-14
Repurchase of common stock, Shares	0							0
Cash dividends declared: $0.96 for 2015, $0.92 for 2014 and $0.80 for 2013 per common share	-214					-214
Other	9			-2	9	2
Ending Balance, Total Equity at Mar. 31, 2014	10,318		4	6,552	23	11,453	-3	-9,507	1,796
Ending Balance, McKesson Stockholders' Equity at Mar. 31, 2014	8,522
Ending Balance, McKesson Stockholders' Equity, Shares at Mar. 31, 2014			381
Ending Balance, McKesson Stockholders' Equity, Treasury Stock, Shares at Mar. 31, 2014	-150							-150
Issuance of shares under employee plans	43		0	152				-109
Issuance of shares under employee plans, shares			3					0
Share-based compensation	165			165
Tax benefit related to issuance of shares under employee plans	105			105
Reclassification from total equity to redeemable noncontrolling interests	-1,500								-1,500
Purchase of noncontrolling interest	-62			-2					-60
Conversion of Celesio convertible bonds	0
Other comprehensive income (loss)							-1,710		-174
Other Comprehensive Income Loss Net Of Tax Excluding Redeemable Noncontrolling Interest	-1,884
Other Comprehensive Income (Loss), Net of Tax	-1,989
Net Income Attributable to McKesson	1,476
Net income (loss) attributable to noncontrolling interests	67								5
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Redeemable Noncontrolling Interest	1,481
Net Income	1,543
Repurchase of common stock	-340	[1]						-340
Repurchase of common stock, Shares	-1.5	[1],[2],[3]						-2
Cash dividends declared: $0.96 for 2015, $0.92 for 2014 and $0.80 for 2013 per common share	-226					-226
Other	-15			-4	-30	2			17
Ending Balance, Total Equity at Mar. 31, 2015	8,085		4	6,968	-7	12,705	-1,713	-9,956	84
Ending Balance, McKesson Stockholders' Equity at Mar. 31, 2015	$8,001
Ending Balance, McKesson Stockholders' Equity, Shares at Mar. 31, 2015			384
Ending Balance, McKesson Stockholders' Equity, Treasury Stock, Shares at Mar. 31, 2015	-152							-152
[1]	This table does not include shares tendered to satisfy the exercise price in connection with cashless exercises of employee stock options or shares tendered to satisfy tax withholding obligations in connection with employee equity awards.
[2]	All of the shares purchased were part of the publicly announced programs.
[3]	The number of shares purchased reflects rounding adjustments.

Consolidated_Statements_of_Sto1

Consolidated Statements of Stockholders' Equity (Parentheticals) (USD $)	0 Months Ended		12 Months Ended
	Jul. 26, 2013	Jul. 25, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per common share	$0.24	$0.20	$0.96	$0.92	$0.80

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Operating Activities
Net Income	$1,543		$1,258		$1,338
Adjustments to reconcile to net cash provided by operating activities:
Depreciation	306		185		143
Amortization	711		550		438
Other deferred taxes	171		17		615
Share-based compensation expense	174		160		167
Gain on business combination	0		0		-81
Asset fair value adjustment	241		80
Impairment of an equity investment	0		0		191
LIFO expense	337		311		13
Other non-cash items	47		130		90
Changes in operating assets and liabilities, net of acquisitions:
Receivables	-2,821		-868		318
Inventories	-2,144		-1,182		-60
Drafts and accounts payable	4,718		2,412		-125
Deferred revenue	-141		-81		-44
Taxes	-222		218		-98
Claims and litigation charges	150		68		72
Litigation settlement payments	0		-105		-483
Other	42		-17		-11
Net cash provided by operating activities	3,112		3,136		2,483
Investing Activities
Property acquisitions	-376	[1]	-278	[1]	-241	[1]
Capitalized software expenditures	-169		-141		-159
Acquisitions, net of cash and cash equivalents acquired	-170		-4,634		-1,873
Proceeds from sale of business	15		97		0
Other	23		-90		64
Net cash used in investing activities	-677		-5,046		-2,209
Financing Activities
Proceeds from Bridge Loan	3,100		6,080		2,225
Repayments of short-term borrowings	-3,152		-6,132		-2,625
Proceeds from issuances of long-term debt	3		4,124		1,798
Repayments of long-term debt	-353		-348		-1,143
Common stock transactions:
Issuances	152		177		166
Share repurchases, including shares surrendered for tax withholding	-450		-130		-1,214
Dividends paid	-227		-214		-194
Other	-41		62		31
Net cash used in financing activities	-968		3,619		-956
Effect of exchange rate changes on cash and cash equivalents	-319		28		-11
Net decrease in cash and cash equivalents	1,148		1,737		-693
Cash and cash equivalents at beginning of year	4,193		2,456		3,149
Cash and cash equivalents at end of year	5,341		4,193		2,456
Cash paid for:
Interest	359		255		207
Income taxes, net of refunds	866		508		55
Non-cash item:
Fair value of debt assumed on acquisition	0		-2,312		-635
Conversion of Celesio convertible bonds	$0		$313		$0
[1]	Long-lived assets consist of property, plant and equipment.

Significant_Accounting_Policie

Significant Accounting Policies	12 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies
	Nature of Operations: McKesson Corporation (“McKesson,” the “Company,” the “Registrant” or “we” and other similar pronouns) delivers pharmaceuticals, medical supplies and healthcare information technology that make healthcare safer while reducing costs. We conduct our business through two operating segments, McKesson Distribution Solutions and McKesson Technology Solutions, as further described in Financial Note 26, “Segments of Business.”
	Basis of Presentation: The consolidated financial statements and accompanying notes are prepared in accordance with U. S. generally accepted accounting principles (“GAAP”). The consolidated financial statements of McKesson include the financial statements of all wholly-owned subsidiaries and majority-owned or controlled companies. We also evaluate our ownership, contractual and other interests in entities to determine if they are variable interest entities (“VIEs”), if we have a variable interest in those entities and the nature and extent of those interests. Refer to Financial Note 16, “Variable Interest Entities” for more information on VIEs. Investments in business entities in which we do not have control, but have the ability to exercise significant influence over operating and financial policies, are accounted for using the equity method and our proportionate share of income or loss is recorded in other income, net. Equity investments in non-publicly traded entities are primarily accounted for using the cost method. Intercompany transactions and balances have been eliminated.
	Fiscal Period: The Company’s fiscal year begins on April 1 and ends on March 31. Unless otherwise noted, all references to a particular year shall mean the Company’s fiscal year.
	Reclassifications: Certain prior year amounts have been reclassified to conform to the current year presentation.
	Use of Estimates: The preparation of financial statements in conformity with U.S. GAAP requires that we make estimates and assumptions that affect the reported amounts in the consolidated financial statements and accompanying notes. Actual amounts could differ from those estimated amounts.
	Cash and Cash Equivalents: All highly liquid debt instruments purchased with original maturity of three months or less at the date of acquisition are included in cash and cash equivalents.
	Cash equivalents, which are available-for-sale, are carried at fair value. Cash equivalents are primarily invested in AAA rated prime and U.S. government money market funds denominated in U.S. dollars, AAA rated prime money market funds denominated in Euros, overnight repurchase agreements collateralized by U.S. government securities, Canadian government securities and/or securities that are guaranteed or sponsored by the U.S. government and an AAA rated prime money market fund denominated in British pound sterling.
	The remaining cash and cash equivalents are deposited with several financial institutions. Deposits at U.S. banks exceed the amount insured by the Federal Deposit Insurance Corporation. We mitigate the risk of our short-term investment portfolio by depositing funds with reputable financial institutions and monitoring risk profiles and investment strategies of money market funds.
	Restricted Cash: Cash that is subject to legal restrictions or is unavailable for general operating purposes is classified as restricted cash and is included within prepaid expenses and other for current balances and other assets for non-current balances in the consolidated balance sheets. At March 31, 2015 and 2014, restricted cash was not material.
	Marketable Securities Available-for-Sale: We carry our marketable securities, which are available-for-sale, at fair value and they are included in prepaid expenses and other in the consolidated balance sheets. The unrealized gains and losses, net of the related tax effect, computed in marking these securities to market have been reported within stockholders’ equity. At March 31, 2015 and 2014, marketable securities were not material.
	In determining whether an other-than-temporary decline in market value has occurred, we consider the duration that, and extent to which, the fair value of the investment is below its cost, the financial condition and future prospects of the issuer or underlying collateral of a security, and our intent and ability to retain the security in order to allow for an anticipated recovery in fair value. Other-than-temporary declines in fair value from amortized cost for available-for-sale equity securities that we intend to sell or would more likely than not be required to sell before the expected recovery of the amortized cost basis are charged to other income, net, in the period in which the loss occurs.
	Concentrations of Credit Risk and Receivables: Our trade receivables are subject to a concentration of credit risk with customers primarily in our Distribution Solutions segment. During 2015, sales to our ten largest customers accounted for approximately 44% of our total consolidated revenues. Sales to our largest customer, CVS Caremark Corporation (“CVS”), accounted for approximately 15% of our total consolidated revenues. At March 31, 2015, trade accounts receivable from our ten largest customers were approximately 36% of total trade accounts receivable. Accounts receivable from CVS were approximately 14% of total trade accounts receivable. As a result, our sales and credit concentration is significant. We also have agreements with group purchasing organizations (“GPOs”), each of which functions as a purchasing agent on behalf of member hospitals, pharmacies and other healthcare providers. The accounts receivables balances are with individual members of the GPOs. A default in payment, a material reduction in purchases from these or any other large customers, or the loss of a large customer or customer groups could have a material adverse impact on our financial condition, results of operations and liquidity. In addition, trade receivables are subject to a concentration of credit risk with customers in the institutional, retail and healthcare provider sectors, which can be affected by a downturn in the economy and changes in reimbursement policies. This credit risk is mitigated by the size and diversity of the customer base as well as its geographic dispersion. We estimate the receivables for which we do not expect full collection based on historical collection rates and ongoing evaluations of the creditworthiness of our customers. An allowance is recorded in our consolidated financial statements for these amounts.
	Financing Receivables: We assess and monitor credit risk associated with financing receivables, namely lease and notes receivables, through regular review of our collection experience in determining our allowance for loan losses. On an ongoing basis, we also evaluate credit quality of our financing receivables utilizing aging of receivables and write-offs, as well as considering existing economic conditions, to determine if an allowance is necessary. Financing receivables are derecognized if legal title to them has been transferred and all related risks and rewards incidental to ownership have passed to the buyer.  As of March 31, 2015 and 2014, financing receivables and the related allowance were not material to our consolidated financial statements.
	Inventories: We report inventories at the lower of cost or market (“LCM”). Inventories for our Distribution Solutions segment consist of merchandise held for resale. For our Distribution Solutions segment, the majority of the cost of domestic inventories is determined using the last-in, first-out (“LIFO”) method. The majority of the cost of inventories held in foreign locations is based on weighted average purchase prices using the first-in, first-out method. Technology Solutions segment inventories consist of computer hardware with cost generally determined by the standard cost method, which approximates average cost. Rebates, cash discounts, and other incentives received from vendors are accounted for as a reduction in the cost of inventory and are recognized when the inventory is sold.
	The LIFO method was used to value approximately 73% and 67% of our inventories at March 31, 2015 and 2014. If we had used the FIFO method of inventory valuation, which approximates current replacement costs, inventories would have been approximately $768 million and $431 million higher than the amounts reported at March 31, 2015 and 2014, respectively. These amounts are equivalent to our LIFO reserves. Our LIFO valuation amount includes both pharmaceutical and non-pharmaceutical products. In 2015, 2014 and 2013, we recognized LIFO related expenses of $337 million, $311 million and $13 million in cost of sales within our consolidated statements of operations. A LIFO expense is recognized when the net effect of price increases on branded pharmaceuticals and non-pharmaceutical products held in inventory exceeds the impact of price declines and shifts towards generic pharmaceuticals, including the effect of branded pharmaceutical products that have lost market exclusivity. A LIFO credit is recognized when the net effect of price declines and shifts towards generic pharmaceuticals exceeds the impact of price increases on branded pharmaceuticals and non-pharmaceutical products held in inventory.
	We believe that the average inventory costing method provides a reasonable estimation of the current cost of replacing inventory (i.e., “market”).  As such, our LIFO inventory is valued at the lower of LIFO or market.  Due to cumulative net price deflation from 2005 to 2013, we had a lower-of-cost or market (“LCM”) reserve of $60 million at March 31, 2013 which reduced pharmaceutical inventories at LIFO to market.  During 2014, the LCM reserve of $60 million was released, resulting in an increase in gross profit.  As of March 31, 2014 and 2015, inventories at LIFO did not exceed market.
	Shipping and Handling Costs: We include costs to warehouse, pick, pack and deliver inventory to our customers in selling, distribution and administrative expenses.
	Property, Plant and Equipment: We state our property, plant and equipment at cost and depreciate them under the straight-line method at rates designed to distribute the cost of properties over estimated service lives ranging from one to thirty years.
	Goodwill: Goodwill is tested for impairment on an annual basis in the fourth quarter or more frequently if indicators for potential impairment exist. Impairment testing is conducted at the reporting unit level, which is generally defined as a component — one level below our Distribution Solutions and Technology Solutions operating segments, for which discrete financial information is available and segment management regularly reviews the operating results of that unit.
	The first step in goodwill testing requires us to compare the estimated fair value of a reporting unit to its carrying value. This step may be performed utilizing either a qualitative or quantitative assessment. If the carrying value of the reporting unit is lower than its estimated fair value, no further evaluation is necessary. If the carrying value of the reporting unit is higher than its estimated fair value, the second step must be performed to measure the amount of impairment loss. Under the second step, the implied fair value of goodwill is calculated in a hypothetical analysis by subtracting the fair value of all assets and liabilities of the reporting unit, including any unrecognized intangible assets, from the fair value of the reporting unit calculated in the first step of the impairment test. If the carrying value of goodwill for the reporting unit exceeds the implied fair value of goodwill, an impairment charge is recorded for that excess.
	To estimate the fair value of our reporting units, we use a combination of the market approach and the income approach. Under the market approach, we estimate fair value by comparing the business to similar businesses or guideline companies whose securities are actively traded in public markets. Under the income approach, we use a discounted cash flow model in which cash flows anticipated over several periods, plus a terminal value at the end of that time horizon, are discounted to their present value using an appropriate expected rate of return. The discount rate used for cash flows reflects capital market conditions and the specific risks associated with the business. In addition, we compare the aggregate of the reporting units’ fair value to the Company’s market capitalization as a further corroboration of the fair values. The testing requires a complex series of assumptions and judgment by management in projecting future operating results, selecting guideline companies for comparisons and assessing risks. The use of alternative assumptions and estimates could affect the fair values and change the impairment determinations.
	Intangible Assets: Currently all of our intangible assets are subject to amortization and are amortized based on the pattern of their economic consumption or on a straight-line basis over their estimated useful lives, ranging from one to thirty-eight years. We review intangible assets for impairment whenever events or changes in circumstances indicate that the carrying value of the assets may not be recoverable. Determination of recoverability is based on the lowest level of identifiable estimated future undiscounted cash flows resulting from use of the asset and its eventual disposition. Measurement of any impairment loss is based on the excess of the carrying value of the asset over its fair market value.
	Capitalized Software Held for Sale: Development costs for software held for sale, which primarily pertain to our Technology Solutions segment, are capitalized once a project has reached the point of technological feasibility. Completed projects are amortized after reaching the point of general availability using the straight-line method based on an estimated useful life of approximately three years. At each balance sheet date, or earlier if an indicator of an impairment exists, we evaluate the recoverability of unamortized capitalized software costs based on estimated future undiscounted revenues net of estimated related costs over the remaining amortization period.
	Capitalized Software Held for Internal Use: We capitalize costs of software held for internal use during the application development stage of a project and amortize those costs over their estimated useful lives ranging from one to ten years. As of March 31, 2015 and 2014, capitalized software held for internal use was $435 million and $508 million, net of accumulated amortization of $1,112 million and $1,004 million, and was included in other assets in the consolidated balance sheets.
	Insurance Programs: Under our insurance programs, we seek to obtain coverage for catastrophic exposures as well as those risks required to be insured by law or contract. It is our policy to retain a significant portion of certain losses primarily related to workers’ compensation and comprehensive general, product and vehicle liability. Provisions for losses expected under these programs are recorded based upon our estimate of the aggregate liability for claims incurred as well as for claims incurred but not yet reported. Such estimates utilize certain actuarial assumptions followed in the insurance industry.
	Revenue Recognition:
	Distribution Solutions
	Revenues for our Distribution Solutions segment are recognized when product is delivered and title passes to the customer or when services have been rendered and there are no further obligations to the customer.
	Revenues are recorded net of sales returns, allowances, rebates and other incentives. Our sales return policy generally allows customers to return products only if they can be resold for value or returned to suppliers for full credit. Sales returns are accrued based on estimates at the time of sale to the customer. Sales returns from customers were approximately $2.7 billion in 2015 and $1.9 billion in 2014 and 2013. Taxes collected from customers and remitted to governmental authorities are presented on a net basis; that is, they are excluded from revenues.
	Revenues for our Distribution Solutions segment include large volume sales of pharmaceuticals primarily to a limited number of large customers who warehouse their own product. We order bulk product from the manufacturer, receive and process the product primarily through our central distribution facility and deliver the bulk product (generally in the same form as received from the manufacturer) directly to our customers’ warehouses. We also record revenues for direct store deliveries from most of these same customers. Direct store deliveries are shipments from the manufacturer to our customers of a limited category of products that require special handling. We assume the primary liability to the manufacturer for these products.
	Revenues are recorded gross when we are the primary party obligated in the transaction, take title to and possession of the inventory, are subject to inventory risk, have latitude in establishing prices, assume the risk of loss for collection from customers as well as delivery or return of the product, are responsible for fulfillment and other customer service requirements, or the transactions have several but not all of these indicators.
	Our Distribution Solutions segment also engages in multiple-element arrangements, which may contain a combination of various products and services. Revenue from a multiple-element arrangement is allocated to the separate elements based on their relative selling price and recognized in accordance with the revenue recognition criteria applicable to each element. Relative selling price is determined based on vendor-specific objective evidence (“VSOE”) of selling price, if available, third-party evidence (“TPE”), if VSOE of selling price is not available, or estimated selling price (“ESP”), if neither VSOE of selling price nor TPE is available.
	Technology Solutions
	Revenues for our Technology Solutions segment are generated primarily by licensing software and software systems (consisting of software, hardware and maintenance support), providing software as a service or SaaS-based solutions and providing claims processing, outsourcing and professional services. Revenue for this segment is recognized as follows:
	Software systems are marketed under information systems agreements as well as service agreements. Perpetual software arrangements are recognized at the time of delivery or under the percentage-of-completion method if the arrangements require significant production, modification or customization of the software. Contracts accounted for under the percentage-of-completion method are generally measured based on the ratio of labor hours incurred to date to total estimated labor hours to be incurred. Changes in estimates to complete and revisions in overall profit estimates on these contracts are charged to earnings in the period in which they are determined. We accrue for contract losses if and when the current estimate of total contract costs exceeds total contract revenue.
	Revenue from time-based software license agreements is recognized ratably over the term of the agreement. Software implementation fees are recognized as the work is performed or under the percentage-of-completion method. Maintenance and support agreements are marketed under annual or multi-year agreements and are recognized ratably over the period covered by the agreements. Hardware revenues are generally recognized upon delivery.
	SaaS-based subscription, content and transaction processing fees are generally marketed under annual and multi-year agreements and are recognized ratably over the contracted terms beginning on the service start date for fixed fee arrangements and recognized as transactions are performed beginning on the service start date for per-transaction fee arrangements. Remote processing service fees are recognized monthly as the service is performed. Outsourcing service revenues are recognized as the service is performed.
	We also offer certain products on an application service provider basis, making our software functionality available on a remote hosting basis from our data centers. The data centers provide system and administrative support, as well as hosting services. Revenue on products sold on an application service provider basis is recognized on a monthly basis over the term of the contract beginning on the service start date of products hosted.
	This segment engages in multiple-element arrangements, which may contain any combination of software, hardware, implementation, SaaS-based offerings, consulting services or maintenance services. For multiple-element arrangements that do not include software, revenue is allocated to the separate elements based on their relative selling price and recognized in accordance with the revenue recognition criteria applicable to each element. Relative selling price is determined based on VSOE of selling price if available, TPE, if VSOE of selling price is not available, or ESP if neither VSOE of selling price nor TPE is available. For multiple-element arrangements accounted for in accordance with specific software accounting guidance when some elements are delivered prior to others in an arrangement and VSOE of fair value exists for the undelivered elements, revenue for the delivered elements is recognized upon delivery of such items. The segment establishes VSOE for hardware and implementation and consulting services based on the price charged when sold separately, and for maintenance services, based on renewal rates offered to customers. Revenue for the software element is recognized under the residual method only when fair value has been established for all of the undelivered elements in an arrangement. If fair value cannot be established for any undelivered element, all of the arrangement’s revenue is deferred until the delivery of the last element or until the fair value of the undelivered element is determinable. For multiple-element arrangements with both software elements and nonsoftware elements, arrangement consideration is allocated between the software elements as a whole and nonsoftware elements.  The segment then further allocates consideration to the individual elements within the software group, and revenue is recognized for all elements under the applicable accounting guidance and our policies described above.
	Supplier Incentives: Fees for service and other incentives received from suppliers, relating to the purchase or distribution of inventory, are generally reported as a reduction to cost of goods sold. We consider these fees and other incentives to represent product discounts and as a result, the amounts are recorded as a reduction of product cost and are recognized through cost of goods sold upon the sale of the related inventory.
	Supplier Reserves: We establish reserves against amounts due from suppliers relating to various price and rebate incentives, including deductions or billings taken against payments otherwise due to them. These reserve estimates are established based on judgment after considering the status of current outstanding claims, historical experience with the suppliers, the specific incentive programs and any other pertinent information available. We evaluate the amounts due from suppliers on a continual basis and adjust the reserve estimates when appropriate based on changes in factual circumstances. As of March 31, 2015 and 2014 supplier reserves were $167 million and $181 million. The ultimate outcome of any outstanding claims may be different than our estimate. All of the supplier reserves at March 31, 2015 and 2014 pertain to our Distribution Solutions segment.
	Income Taxes: We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statements and the tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Tax benefits from uncertain tax positions are recognized when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. The amount recognized is measured as the largest amount of tax benefit that is greater than 50 percent likely of being realized upon effective settlements. Deferred taxes are not provided on undistributed earnings of our foreign operations that are considered to be permanently reinvested.
	Foreign Currency Translation: Our international subsidiaries generally consider their local currency to be their functional currency. Assets and liabilities of these international subsidiaries are translated into U.S. dollars at year-end exchange rates and revenues and expenses are translated at average exchange rates during the year. Currency translation adjustments for the year are included in other comprehensive income or loss in the statements of consolidated comprehensive income, and the cumulative effect is included in the stockholders’ equity section of the consolidated balance sheets. When we sell all or substantially all of an international entity, the related share of the cumulative currency translation adjustment is removed from stockholders’ equity and is included in the gain or loss on sale in the consolidated statements of operations. Realized gains and losses from currency exchange transactions are recorded in operating expenses in the consolidated statements of operations and were not material to our consolidated results of operations in 2015, 2014 or 2013.
	Derivative Financial Instruments: Derivative financial instruments are used principally in the management of foreign currency and interest rate exposures and are recorded on the consolidated balance sheets at fair value. If a derivative is designated as a fair value hedge, the changes in the fair value of the derivative and of the hedged item attributable to the hedged risk are recognized as a charge or credit to earnings. If the derivative is designated as a cash flow hedge, the effective portions of changes in the fair value of the derivative are included in other comprehensive income or loss in the statements of consolidated comprehensive income, and the cumulative effect is included in the stockholders’ equity section of the consolidated balance sheets. The cumulative changes in fair value are reclassed to the consolidated statements of operations when the hedged item affects earnings. We periodically evaluate hedge effectiveness, and ineffective portions of changes in the fair value of cash flow hedges are recognized as a charge or credit to earnings. Derivative instruments not designated as hedges are marked-to-market at the end of each accounting period with the change included in earnings.
	Comprehensive Income: Comprehensive income consists of two components, net income and other comprehensive income. Other comprehensive income refers to revenue, expenses, and gains and losses that under GAAP are recorded as an element of shareholders’ equity but are excluded from net income. Our other comprehensive income consists of foreign currency translation adjustments from those subsidiaries where the local currency is the functional currency, unrealized gains and losses on cash flow hedges, as well as unrealized gains and losses on retirement-related benefit plans.
	Noncontrolling and Redeemable Noncontrolling Interests: Noncontrolling interests represent the portion of profit or loss, net assets and comprehensive income that is not allocable to McKesson Corporation. In 2015, net income attributable to noncontrolling interests primarily represents guaranteed dividends and recurring compensation that McKesson is obligated to pay to the noncontrolling shareholders of Celesio. Noncontrolling interests with redemption features, such as put rights, that are not solely within the Company’s control are considered redeemable noncontrolling interests.  Redeemable noncontrolling interests are presented outside of Stockholders’ Equity on our consolidated balance sheet. Refer to Financial Note 3, “Noncontrolling Interests,” for more information.
	Share-Based Compensation: We account for all share-based compensation transactions using a fair-value based measurement method. The share-based compensation expense, for the portion of the awards that is ultimately expected to vest, is recognized on a straight-line basis over the requisite service period. The compensation expense recognized has been classified in the consolidated statements of operations or capitalized on the consolidated balance sheets in the same manner as cash compensation paid to our employees.
	Loss Contingencies: We are subject to various claims, other pending and potential legal actions for damages, investigations relating to governmental laws and regulations and other matters arising out of the normal conduct of our business. When a loss is considered probable and reasonably estimable, we record a liability in the amount of our best estimate for the ultimate loss. However, the likelihood of a loss with respect to a particular contingency is often difficult to predict and determining a meaningful estimate of the loss or a range of loss may not be practicable based on the information available and the potential effect of future events and decisions by third parties that will determine the ultimate resolution of the contingency. Moreover, it is not uncommon for such matters to be resolved over many years, during which time relevant developments and new information must be reevaluated at least quarterly to determine both the likelihood of potential loss and whether it is possible to reasonably estimate a range of possible loss. When a loss is probable but a reasonable estimate cannot be made, disclosure of the proceeding is provided.
	Disclosure also is provided when it is reasonably possible that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the recorded provision. We review all contingencies at least quarterly to determine whether the likelihood of loss has changed and to assess whether a reasonable estimate of the loss or range of the loss can be made. As discussed above, development of a meaningful estimate of loss or a range of potential loss is complex when the outcome is directly dependent on negotiations with or decisions by third parties, such as regulatory agencies, the court system and other interested parties. Such factors bear directly on whether it is possible to reasonably estimate a range of potential loss and boundaries of high and low estimate.
	Business Combinations: We account for acquired businesses using the acquisition method of accounting, which requires that once control is obtained of a business, 100% of the assets acquired and liabilities assumed, including amounts attributed to noncontrolling interests, be recorded at the date of acquisition at their respective fair values. Any excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill. Acquisition-related expenses and related restructuring costs are expensed as incurred.
	Several valuation methods may be used to determine the fair value of assets acquired and liabilities assumed.  For intangible assets, we typically use the income method.  This method starts with a forecast of all of the expected future net cash flows for each asset.  These cash flows are then adjusted to present value by applying an appropriate discount rate that reflects the risk factors associated with the cash flow streams.  Some of the more significant estimates and assumptions inherent in the income method or other methods include the amount and timing of projected future cash flows, the discount rate selected to measure the risks inherent in the future cash flows and the assessment of the asset’s life cycle and the competitive trends impacting the asset, including consideration of any technical, legal, regulatory, or economic barriers to entry.  Determining the useful life of an intangible asset also requires judgment as different types of intangible assets will have different useful lives and certain assets may even be considered to have indefinite useful lives.
	Recently Adopted Accounting Pronouncements
	Business Combinations: In November 2014, amended guidance related to pushdown accounting was issued and became effective immediately. This guidance provides an acquired entity with an option to use the acquirer’s accounting and reporting basis in the preparation of its separate financial statements when an acquirer obtains control of the acquired entity. The option to apply pushdown accounting can be elected for each individual change-of-control event.  The adoption of this amended guidance did not have a material effect on our consolidated financial statements.
	Cumulative Translation Adjustment: In the first quarter of 2015, we adopted amended guidance for parent’s accounting for the cumulative translation adjustment upon derecognition of certain subsidiaries or group of assets within a foreign entity or of an investment in a foreign entity.  The amended guidance requires the release of any cumulative translation adjustment into net income only upon complete or substantially complete liquidation of a controlling interest in a subsidiary or a group of assets within a foreign entity.  Also, it requires the release of all or a pro rata portion of the cumulative translation adjustment to net income in the case of sale of an equity method investment that is a foreign entity.  The adoption of this amended guidance did not have a material effect on our consolidated financial statements.
	Recently Issued Accounting Pronouncements Not Yet Adopted
	Fees Paid in a Cloud Computing Arrangement:  In April 2015, amended guidance was issued for a customer’s accounting for fees paid in a cloud computing arrangement.  The amended guidance requires customers to determine whether or not an arrangement contains a software license element. If the arrangement contains a software element, the related fees paid should be accounted for as an acquisition of a software license. If the arrangement does not contain a software license, it is accounted for as a service contract. The amended guidance will become effective for us commencing in the first quarter of 2017.  Early adoption is permitted.  We are currently evaluating the impact of this amended guidance on our consolidated financial statements.
	Debt Issuance Costs:  In April 2015, amended guidance was issued for the balance sheet presentation of debt issuance costs and will become effective for us commencing in the first quarter of 2017.  Early adoption is permitted.  The amended guidance requires debt issuance costs related to a recognized debt liability be reported in the balance sheet as a direct deduction from the carrying amount of that debt liability.  The recognition and measurement guidance for debt issuance costs are not affected by the amended guidance. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements.
	Consolidation: In February 2015, amended guidance was issued for consolidating legal entities in which a reporting entity holds a variable interest.  The amended guidance modifies the evaluation of whether limited partnerships and similar legal entities are VIEs and changes the consolidation analysis of reporting entities that are involved with VIEs that have fee arrangements and related party relationships. The amended guidance will become effective for us commencing in the first quarter of 2017.  Early adoption is permitted.  We are currently evaluating the impact of this amended guidance on our consolidated financial statements.
	Discontinued Operations: In April 2014, amended guidance was issued for reporting of discontinued operations and disclosures of disposals of components.  The amended guidance revises the criteria for disposals to qualify as discontinued operations and permits significant continuing involvement and continuing cash flows with the discontinued operation.  In addition, the amended guidance requires additional disclosures for discontinued operations and new disclosures for individually material disposal transactions that do not meet the definition of a discontinued operation.  The amended guidance is effective for us prospectively commencing in the first quarter of 2016.  Early adoption is permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements.
	Revenue Recognition: In May 2014, amended guidance was issued for recognizing revenue from contracts with customers.  The amended guidance eliminated industry specific guidance and applies to all companies.  Revenues will be recognized when an entity satisfies a performance obligation by transferring control of a promised good or service to a customer in an amount that reflects the consideration to which the entity expects to be entitled for that good or service. Revenue from a contract that contains multiple performance obligations is allocated to each performance obligation generally on a relative standalone selling price basis. The amended guidance also requires additional quantitative and qualitative disclosures. The amended guidance is effective for us commencing in the first quarter of 2018.  The amended guidance allows for either full retrospective adoption or modified retrospective adoption. Early adoption is not permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements.

Business_Combinations

Business Combinations	12 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Business Combinations	Business Combinations
	Fiscal 2014
	On February 6, 2014, we completed the acquisition of 77.6% of the then outstanding common shares of Celesio AG (“Celesio”) and certain convertible bonds of Celesio for cash consideration of $4.5 billion, net of cash acquired (the “Acquisition”). Upon the acquisition, our ownership of Celesio’s fully diluted common shares was 75.6% and, as required, we consolidated Celesio’s debt with a fair value of $2.3 billion as a liability on our consolidated balance sheet. The Acquisition was initially funded by utilizing a senior bridge loan, our existing accounts receivable sales facility and cash on hand. Celesio is an international wholesale and retail company and a provider of logistics and services to the pharmaceutical and healthcare sectors. Celesio’s headquarters is in Stuttgart, Germany and it operates in 14 countries around the world. The acquisition of Celesio expanded our global geographic area. Financial results for Celesio are included within our International pharmaceutical distribution and services business, which is part of our Distribution Solutions segment, since the date of Acquisition.
	From February 7, 2014 through March 31, 2014, substantially all of the convertible bonds issued by Celesio (held by both third parties and us) were converted into an additional 20.9 million common shares of Celesio and approximately $30 million in cash. At March 31, 2014, we owned approximately 75.4% of Celesio’s outstanding and fully diluted common shares.
	The fair value measurements of the assets acquired and liabilities assumed of Celesio as of the acquisition date were finalized upon completion of the measurement period.  The following table summarizes the final amounts of the fair value recognized for the assets acquired and liabilities assumed as of the acquisition date as well as adjustments made during the measurement period.  Among the adjustments recorded, the fair value of the acquired intangible assets decreased by $709 million.  The fair value was primarily determined by applying the income approach using unobservable inputs for projected cash flows, which were refined during the measurement period and are considered Level 3 inputs under the fair value measurements and disclosure guidance. These refinements did not have a significant impact on our consolidated statements of operations, balance sheets or cash flows in any period and, therefore, we have not retrospectively adjusted our financial statements.
	(In millions)	Amounts			Measurement Period Adjustments			Amounts Recognized as of Acquisition Date (Final as Adjusted)
		Previously Recognized as of
		Acquisition Date
		(Provisional)
	Receivables	$	3,425		$	(49	)	$	3,376
	Other current assets, net of cash and cash equivalents acquired	2,413			17			2,430
	Goodwill	3,570			655			4,225
	Intangible assets	3,018			(709		)	2,309
	Other long-term assets	1,272			(39		)	1,233
	Current liabilities	(4,096		)	(28		)	(4,124		)
	Short-term borrowings and current portion of long-term debt	(1,990		)	—			(1,990		)
	Long-term debt	(322		)	—			(322		)
	Other long-term liabilities	(1,293		)	158			(1,135		)
	Fair value of net assets, less cash and cash equivalents	5,997			5			6,002
	Less: Noncontrolling Interests	(1,500		)	(5		)	(1,505		)
	Net assets acquired, net of cash and cash equivalents	$	4,497		$	—		$	4,497
	The excess of the purchase price and the noncontrolling interests over the fair value of the acquired net assets has been allocated to goodwill, which primarily reflects the expected future benefits to be realized upon integrating the business. Most of the goodwill is not expected to be deductible for tax purposes.
	Domination and Profit and Loss Transfer Agreement
	On May 22, 2014, Celesio and McKesson, through its wholly-owned subsidiary, McKesson Deutschland GmbH & Co. KGaA (“McKesson Deutschland,” formerly known as Dragonfly GmbH & Co. KGaA), entered into the domination and profit and loss transfer agreement (the “Domination Agreement”) subject to Celesio shareholder approval and German registration requirements. Under the Domination Agreement, Celesio subordinates its management to McKesson and undertakes to transfer all of its annual profits to McKesson, and McKesson undertakes to compensate any annual losses incurred by Celesio and to grant, subject to a potential court review, the noncontrolling shareholders of Celesio (i) an annual recurring compensation of €0.83 per Celesio share (“Compensation Amount”), (ii) a one-time dividend for Celesio’s fiscal year ended December 31, 2014 of €0.83 per Celesio share reduced accordingly for any dividend paid by Celesio in relation to its fiscal year ended December 31, 2014 (“Guaranteed Dividend”) and (iii) a right to put (“Put Right”) their Celesio shares at €22.99 per share increased annually for interest in the amount of 5 percentage points above a base rate published by the German Bundesbank semiannually, less any Compensation Amount or Guaranteed Dividend already paid in respect of the relevant time period (“Put Amount”). The Domination Agreement does not have an expiration date and can be terminated by McKesson without cause in writing no earlier than March 31, 2020. The Domination Agreement was approved at the general shareholders’ meeting of Celesio on July 15, 2014, approved by the Stuttgart Higher Regional Court for registration on December 2, 2014, and was registered in the commercial register of Celesio at the local court of Stuttgart on December 2, 2014. As a result, McKesson obtained the ability to pursue integration of the two companies on December 2, 2014.
	Under the Domination Agreement, the noncontrolling shareholders of Celesio no longer participate in their percentage ownership of Celesio’s profits and losses, but instead have the right to receive the one-time Guaranteed Dividend and prospectively the Compensation Amount.
	Subsequent to the Domination Agreement’s registration, certain noncontrolling shareholders of Celesio initiated appraisal proceedings (“Appraisal Proceedings”) with the Stuttgart Higher Regional Court to challenge the Compensation Amount, Guaranteed Dividend and/or Put Amount. As long as any Appraisal Proceedings are pending, the Compensation Amount, Guaranteed Dividend and/or Put Amount will be paid as specified currently in the Domination Agreement. If any such Appraisal Proceedings result in an adjustment to the Compensation Amount, Guaranteed Dividend and/or Put Amount, McKesson Deutschland would be required to make certain additional payments for any shortfall to all Celesio noncontrolling shareholders who previously received the Guaranteed Dividend, Compensation Amount and/or Put Amount. The Put Right specified in the Domination Agreement may be exercised until two months after the announcement regarding the end of the Appraisal Proceedings. In addition, if the Domination Agreement is terminated, the Put Right may be exercised for a two-month period after the date of termination.
	On August 14, 2014, Magnetar Capital filed a lawsuit against Celesio with the Stuttgart Regional Court claiming that the shareholders’ approval of the Domination Agreement was void under the German Stock Corporation Act (“Main Proceedings”). As the Domination Agreement was registered in the commercial register of Celesio at the local court of Stuttgart, Germany on December 2, 2014 following the approval for registration by the Stuttgart Higher Regional Court, the outcome of the Main Proceedings will not impact the effectiveness of the Domination Agreement and thus will not impact McKesson’s ability to direct the activities of Celesio. The court is scheduled to issue a decision on the Main Proceedings on June 16, 2015.
	Fiscal 2013
	On February 22, 2013, we acquired all of the outstanding shares of PSS World Medical, Inc. (“PSSI”) of Jacksonville, Florida for $29.00 per share plus the assumption of PSSI’s debt, or approximately $1.9 billion in aggregate, consisting of cash consideration of $1.3 billion, net of cash acquired, and the assumption of long-term debt with a fair value of $0.6 billion. The cash paid at acquisition was funded from cash on hand and the issuance of long-term debt. PSSI markets and distributes medical products and services throughout the United States. The acquisition of PSSI expanded our existing Medical-Surgical business.
	Included in the purchase price allocation are acquired identifiable intangibles of $568 million, the fair value of which was primarily determined by applying the income approach, using several significant unobservable inputs for projected cash flows and a discount rate. These inputs are considered Level 3 inputs under the fair value measurements and disclosure guidance. The excess of the purchase price over the net tangible and intangible assets of approximately $1,149 million was recorded as goodwill, which primarily reflects the expected future benefits to be realized upon integrating the business. Most of the goodwill is not expected to be deductible for tax purposes.
	Financial results for PSSI since the acquisition date are included in the results of operations within our Medical‑Surgical distributions and services business, which is part of our Distribution Solutions segment beginning in the fourth quarter of 2013.
	On April 6, 2012, we purchased the remaining 50% ownership interest in our corporate headquarters building located in San Francisco, California, for $90 million, which was funded from cash on hand.  We previously held a 50% ownership interest and were the primary tenant in this building.  This transaction was accounted for as a step acquisition, which required that we re‑measure our previously held 50% ownership interest to fair value and record the difference between the fair value and carrying value as a gain in the consolidated statements of operations.  The re-measurement to fair value resulted in a non-cash pre-tax gain of $81 million ($51 million after-tax), which was recorded as a gain on business combination within Corporate in the consolidated statements of operations during the first quarter of 2013. The total fair value of the net assets acquired was $180 million, which was allocated as follows: building and improvements of $113 million and land of $58 million with the remainder allocated for settlement of our pre-existing lease and lease intangible assets.
	Other Acquisitions
	During the last three years, we also completed a number of other smaller acquisitions within both of our operating segments. Financial results for our business acquisitions have been included in our consolidated financial statements since their respective acquisition dates. Purchase prices for our business acquisitions have been allocated based on estimated fair values at the date of acquisition.
	Goodwill recognized for our business acquisitions is generally not expected to be deductible for tax purposes. However, if we acquire the assets of a company, the goodwill may be deductible for tax purposes.

Noncontrolling_Interests_Nonco

Noncontrolling Interests Noncontrolling Interests	12 Months Ended
	Mar. 31, 2015
Noncontrolling Interest [Abstract]
Noncontrolling Interest
	3	Noncontrolling Interests
	At March 31, 2014, we owned approximately 75.4% of Celesio’s outstanding and fully diluted common shares and the noncontrolling interests in Celesio were presented within the permanent equity section of our consolidated balance sheet. In April 2014, we completed a tender offer and paid $32 million in cash to acquire approximately 1 million additional common shares of Celesio at €23.50 per share, which increased our ownership share by 0.5% and decreased noncontrolling interests by $35 million.
	On December 2, 2014, the Domination Agreement between Celesio and McKesson, through its wholly-owned subsidiary, McKesson Deutschland, became effective as previously discussed in Financial Note 2, “Business Combinations”. Prior to the effectiveness of the Domination Agreement, the net income or loss from Celesio was attributed to the noncontrolling shareholders of Celesio based on their proportionate ownership interest in Celesio. Upon the effectiveness of the Domination Agreement, McKesson became obligated to pay the $50 million Guaranteed Dividend to the noncontrolling shareholders of Celesio in relation to Celesio’s fiscal year ended December 31, 2014. Under the Domination Agreement, McKesson also became obligated to pay the annual recurring Compensation Amount of €0.83 per Celesio share effective January 1, 2015. The Compensation Amount is recognized ratably during the applicable annual period. As a result, during 2015, we recorded a total attribution of net income to the noncontrolling shareholders of Celesio of $62 million. All amounts were recorded in our consolidated statement of operations within the caption, “Net Income Attributable to Noncontrolling Interests,” and the corresponding liability balance was recorded within other accrued liabilities on our consolidated balance sheet.
	In addition, upon effectiveness of the Domination Agreement, the noncontrolling interests in Celesio became redeemable as a result of a put right. Accordingly, the carrying value of noncontrolling interests related to Celesio of $1.5 billion was reclassified from “Total Equity” to “Redeemable Noncontrolling Interests” on our consolidated balance sheet. During the fourth quarter of 2015, we paid $8 million to purchase 0.3 million shares of Celesio through the exercise of the put right by the noncontrolling shareholders, which decreased the carrying value of redeemable noncontrolling interests by $9 million. The balance of redeemable noncontrolling interests is reported at the greater of its carrying value or its maximum redemption value at each reporting date. The redemption value is the Put Amount adjusted for exchange rate fluctuations each period. At March 31, 2015, the carrying value of redeemable noncontrolling interests of $1.4 billion exceeded the maximum redemption value of $1.2 billion. At March 31, 2015, we owned approximately 76.0% of Celesio’s outstanding common shares.
	Changes in noncontrolling interests and redeemable noncontrolling interests were as follows:
	(In millions)	Noncontrolling			Redeemable
		Interests			Noncontrolling
					Interests
	Balance, March 31, 2014	$	1,796		$	—
	Net income attributable to noncontrolling interests (1)	5			62
	Other comprehensive loss	(174		)	(105		)
	Purchase of noncontrolling interests	(60		)	(9		)
	Reclassification from Total Equity to Redeemable Noncontrolling Interests (2)	(1,500		)	1,500
	Reclassification of guaranteed dividends and recurring compensation to other accrued liabilities	—			(62		)
	Other	17			—
	Balance, March 31, 2015	$	84		$	1,386
	-1	Includes the Guaranteed Dividend of $50 million for Celesio’s fiscal year ended December 31, 2014 and the Compensation Amount of $12 million for the fourth quarter of 2015
	-2	Includes net foreign currency losses of $138 million attributable to noncontrolling interests
	The effect of changes in our ownership interests with noncontrolling interests on our equity of $2 million was recorded as a net decrease to McKesson’s stockholders’ paid-in capital during 2015. Net income attributable to McKesson and transfers from noncontrolling interests amounted to $1,474 million during 2015.

Discontinued_Operations

Discontinued Operations	12 Months Ended
	Mar. 31, 2015
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations
	During the fourth quarter of 2015, we committed to a plan to sell our Brazilian pharmaceutical distribution business and a small business from our Distribution Solutions segment, as well as a small business from our Technology Solutions segment. We acquired the Brazilian distribution business through our February 2014 acquisition of Celesio.
	In 2014, we committed to a plan to sell our International Technology and our Hospital Automation businesses from our Technology Solutions segment and certain businesses from our Distribution Solutions segment. During the first quarter of 2015, we decided to retain the workforce business within our International Technology business. This business consists of workforce management solutions for the National Health Service in the United Kingdom, which we will transition to another service provider during the first quarter of 2016. As a result, the workforce business, which had been designated as a discontinued operation since the first quarter of 2014, was reclassified to continuing operations in the first quarter of 2015. During the first quarter of 2015, we also recorded a non-cash pre-tax charge of $34 million ($27 million after-tax) primarily relating to depreciation and amortization expense for the period in 2014 while the business was classified as held for sale. The non-cash charge was recorded in our consolidated statement of operations primarily in cost of sales.
	As required, we classified the results of operations and cash flows of these businesses as discontinued operations for all applicable periods presented in our consolidated financial statements. Depreciation and amortization expense is not recognized from the date the businesses are classified as held for sale.
	A summary of results of discontinued operations is as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Revenues	$	2,196		$	637		$	259
	Loss from discontinued operations	$	(321	)	$	(177	)	$	(32	)
	Loss on sale	(6		)	(5		)	—
	Loss from discontinued operations before income tax	(327		)	(182		)	(32		)
	Income tax benefit	28			26			7
	Loss from discontinued operations, net of tax	$	(299	)	$	(156	)	$	(25	)
	Fiscal 2015
	During the second quarter of 2015, we completed the sale of a software business within our International Technology business and recorded a pre-tax and after-tax loss of $6 million.
	During the fourth quarter of 2015, we recorded $241 million pre-tax ($235 million after-tax) non-cash impairment charges to reduce the carrying value of our Brazilian distribution business to its estimated fair value, less cost to sell. The impairment charge reduced the carrying value of property, plant and equipment, other long-lived assets and goodwill by $31 million. The remaining difference between the business’ fair value and carrying value of $210 million was recorded as a liability and was included in other accrued liabilities in our consolidated balance sheet. Cumulative foreign currency translation losses of $17 million were included in the assessment of this business’ carrying value for purposes of calculating the impairment charge. Cumulative foreign currency translation losses (net of tax) are included in Accumulated Other Comprehensive Income on our consolidated balance sheet at March 31, 2015. The ultimate loss from the sale may be higher or lower than our current assessment of the business’ fair value.
	Fiscal 2014
	During the third quarter of 2014, we sold our Hospital Automation business for net cash proceeds of $55 million and recorded a pre-tax and after-tax loss of $5 million and $7 million.
	During the third quarter of 2014, we recorded an $80 million non-cash pre-tax and after-tax impairment charge to reduce the carrying value of our International Technology business to its estimated fair value less costs to sell. The impairment charge was primarily attributed to goodwill and other long-lived assets and as a result, there was no tax benefit associated with this charge.
	The assets and liabilities of our discontinued operations were classified as held-for-sale effective in 2014. All applicable assets of the businesses to be sold are included under the caption “Prepaid expenses and other” and all applicable liabilities under the caption “Other accrued liabilities” within our consolidated balance sheet at March 31, 2015 and 2014. The carrying values of the assets and liabilities classified as held-for-sale were $660 million and $663 million at March 31, 2015.

Asset_Impairments_and_Product_

Asset Impairments and Product Alignment Charges	12 Months Ended
	Mar. 31, 2015
Asset Impairment Charges [Abstract]
Asset Impairments and Product Alignment Charges	Asset Impairments and Product Alignment Charges
	In 2014 and 2013, we recorded asset impairments and product alignment charges of $57 million and $46 million in our Technology Solutions segment.
	Fiscal 2014
	During the third quarter of 2014, our Technology Solutions segment recorded pre-tax charges totaling $57 million. These charges primarily consist of $35 million of product alignment charges, $15 million of integration-related expenses and $7 million of reduction-in-workforce severance charges. Included in the total charge was $35 million for severance for employees primarily in our research and development, customer services and sales functions, and $15 million for asset impairments which primarily represents the write-off of deferred costs related to a product that will no longer be developed. Charges were recorded in our consolidated statement of operations as follows: $34 million in cost of sales and $23 million in operating expenses.
	Fiscal 2013
	During the fourth quarter of 2013, we recorded $46 million of non-cash pre-tax impairment charges. These charges were the result of a significant decrease in estimated revenues for a software product. The charge included a $36 million goodwill impairment to reduce the carrying value of goodwill within the applicable reporting unit to its implied fair value. In addition, the goodwill had a nominal tax basis. This impairment charge was recorded in operating expenses within our consolidated statement of operations. Refer to Financial Note 20, “Fair Value Measurements,” for more information on this nonrecurring fair value measurement. The balance of the charge also represents a $10 million impairment to reduce the carrying value of the unamortized capitalized software held for sale costs for this product to its net realizable value. We concluded that the estimated future undiscounted revenues, net of estimated related costs, were insufficient to recover its carrying value. This impairment charge was recorded in cost of sales within our consolidated statement of operations.

Equity_Investments

Equity Investments	12 Months Ended
	Mar. 31, 2015
Equity Method Investment and Joint Venture Disclosure [Abstract]
Equity Method Investments and Joint Ventures Disclosure [Text Block]	Equity Investments
	We own a 45% interest in Brocacef Holding N.V. (“Brocacef”), which provides, through its subsidiaries, wholesale distribution services and supplies pharmaceutical and other healthcare products to pharmacies, retailers and hospitals in the Netherlands. During the third quarter of 2015, we announced that Brocacef intends to purchase Mediq Apotheken Beheer B.V., which owns and operates pharmacies in the Netherlands. This acquisition is subject to customary closing conditions including regulatory clearances and approval of the relevant competition authorities but is expected to close during the first half of 2016.
	During 2013, we committed to a plan to sell our 49% equity interest in Nadro, S.A. de C.V. (“Nadro”) and in the fourth quarter of 2013 we recorded a pre-tax impairment charge of $191 million reducing the investment’s carrying value to its estimated fair value. Cumulative foreign currency translation losses of $69 million were included in the assessment of the investment’s carrying value for purposes of calculating the impairment charge. The impairment charge was recorded in impairment of an equity investment in the consolidated statements of operations within our Distribution Solutions segment.
	In September 2013, we completed the sale of our 49% equity interest in Nadro. Under the terms of the agreement, we received $41 million in total cash consideration. There was no material gain or loss on the disposition based on the adjusted fair value of the investment at the time of the sale. Prior to the sale, our investment in Nadro was accounted for under the equity method of accounting within our Distribution Solutions segment.

ShareBased_Compensation

Share-Based Compensation	12 Months Ended
	Mar. 31, 2015
Share-based Compensation [Abstract]
Share-Based Compensation	Share-Based Compensation
	We provide share-based compensation to our employees, officers and non-employee directors, including stock options, an employee stock purchase plan, restricted stock units (“RSUs”), performance-based restricted stock units (“PeRSUs”) and total shareholder return units (“TSRUs”) (collectively, “share-based awards”). Most of our share-based awards are granted in the first quarter of each fiscal year.
	Compensation expense for the share-based awards is recognized for the portion of awards ultimately expected to vest. We estimate the number of share-based awards that will ultimately vest primarily based on historical experience. The estimated forfeiture rate established upon grant is re-assessed throughout the requisite service period and is adjusted when actual forfeitures occur. The actual forfeitures in future reporting periods could be higher or lower than current estimates.
	The compensation expense recognized has been classified in the consolidated statements of operations or capitalized in the consolidated balance sheets in the same manner as cash compensation paid to our employees. There was no material share-based compensation expense capitalized as part of the cost of an asset in 2015, 2014 and 2013.
	Impact on Net Income
	The components of share-based compensation expense and related tax benefits are as follows:
		Years Ended March 31,
	(In millions)	2015				2014				2013
	Restricted stock unit awards (1)	$	137			$	126			$	132
	Stock options	24				22				24
	Employee stock purchase plan	13				12				11
	Share-based compensation expense	174				160				167
	Tax benefit for share-based compensation expense (2)	(61		)		(55		)		(59		)
	Share-based compensation expense, net of tax	$	113			$	105			$	108
	-1	Includes compensation expense recognized for RSUs, PeRSUs and TSRUs. Our TSRUs were awarded beginning in 2015.
	-2	Income tax benefit is computed using the tax rates of applicable tax jurisdictions. Additionally, a portion of pre-tax compensation expense is not tax-deductible.
	Stock Plans
	In July 2013, our stockholders approved the 2013 Stock Plan to replace the 2005 Stock Plan. These stock plans provide our employees, officers and non-employee directors the opportunity to receive equity-based, long-term incentives in the form of stock options, restricted stock, RSUs, PeRSUs, TSRUs and other share-based awards. The 2013 Stock Plan reserves 30 million shares plus the remaining number of shares reserved but unused under the 2005 Stock Plan. As of March 31, 2015, 30 million shares remain available for future grant under the 2013 Stock Plan.
	Stock Options
	Stock options are granted with an exercise price at no less than the fair market value and those options granted under the stock plans generally have a contractual term of seven years and follow a four-year vesting schedule.
	Compensation expense for stock options is recognized on a straight-line basis over the requisite service period and is based on the grant-date fair value for the portion of the awards that is ultimately expected to vest. We use the Black-Scholes options-pricing model to estimate the fair value of our stock options. Once the fair value of an employee stock option is determined, current accounting practices do not permit it to be changed, even if the estimates used are different from actual. The options-pricing model requires the use of various estimates and assumptions as follows:
	•	Expected stock price volatility is based on a combination of historical volatility of our common stock and implied market volatility. We believe that this market-based input provides a reasonable estimate of our future stock price movements and is consistent with employee stock option valuation considerations.
	•	Expected dividend yield is based on historical experience and investors’ current expectations.
	•	The risk-free interest rate for periods within the expected life of the option is based on the constant maturity U.S. Treasury rate in effect at the time of grant.
	•	Expected life of the options is based primarily on historical employee stock option exercises and other behavior data and reflects the impact of changes in contractual life of current option grants compared to our historical grants.
	Weighted-average assumptions used to estimate the fair value of employee stock options were as follows:
		Years Ended March 31,
		2015		2014		2013
	Expected stock price volatility	22%		22%		27%
	Expected dividend yield	0.60%		0.70%		0.90%
	Risk-free interest rate	1.30%		0.70%		0.80%
	Expected life (in years)	4		4		5
	The following is a summary of stock options outstanding at March 31, 2015:
									Options Outstanding						Options Exercisable
	Range of Exercise								Number of		Weighted-		Weighted-		Number of	Weighted-
	Prices								Options		Average		Average		Options	Average
									Outstanding		Remaining		Exercise Price		Exercisable at	Exercise Price
									at Year End		Contractual				Year End
									(In millions)		Life (Years)				(In millions)
	$	40.46		–	$	133.27			4		3		$	79.38	2	$	68.8
	133.28			–	226.05				1		6		182.38		—	155.87
									5						2
	The following table summarizes stock option activity during 2015:
	(In millions, except per share data)	Shares		Weighted-				Weighted-		Aggregate
				Average				Average		Intrinsic
				Exercise				Remaining		Value (2)
				Price				Contractual
								Term (Years)
	Outstanding, March 31, 2014	6		$	78.07			4		$	473
	Granted	1		184.84
	Exercised	-2		67.64
	Outstanding, March 31, 2015	5		$	95.01			4		$	539
	Vested and expected to vest (1)	5		$	95.01			4		$	538
	Vested and exercisable, March 31, 2015	2		69.27				3		363
	-1	The number of options expected to vest takes into account an estimate of expected forfeitures.
	-2	The intrinsic value is calculated as the difference between the period-end market price of the Company’s common stock and the exercise price of “in-the-money” options.
	The following table provides data related to stock option activity:
		Years Ended March 31,
	(In millions, except per share data)	2015				2014				2013
	Weighted-average grant date fair value per stock option	$	35.49			$	21.45			$	19.63
	Aggregate intrinsic value on exercise	$	153			$	144			$	107
	Cash received upon exercise	$	76			$	111			$	106
	Tax benefits realized related to exercise	$	60			$	55			$	41
	Total fair value of stock options vested	$	20			$	24			$	24
Total compensation cost, net of estimated forfeitures, related to unvested stock options not yet recognized, pre-tax	$	22			$	29			$	37
Weighted-average period in years over which stock option compensation cost is expected to be recognized	2				1				1
Restricted Stock Unit Awards
RSUs, which entitle the holder to receive at the end of a vesting term a specified number of shares of the Company’s common stock, are accounted for at fair value at the date of grant. Total compensation expense for RSUs under our stock plans is determined by the product of the number of shares that are expected to vest and the grant date market price of the Company’s common stock. The Compensation Committee determines the vesting terms at the time of grant. These awards generally vest in three to four years. We recognize expense for RSUs on a straight-line basis over the requisite service period.
Non-employee directors receive an annual grant of RSUs, which vest immediately and are expensed upon grant. The director may elect to receive the underlying shares immediately or defer receipt of the shares if they meet director stock ownership guidelines. The shares will be automatically deferred for those directors who do not meet the director stock ownership guidelines. At March 31, 2015, approximately 158,000 RSUs for our directors are vested.
PeRSUs are RSUs for which the number of RSUs awarded is conditional upon the attainment of one or more performance objectives over a specified period. Each year, the Compensation Committee approves the target number of PeRSUs representing the base number of awards that could be granted if performance goals are attained. PeRSUs are accounted for as variable awards until the performance goals are reached at which time the grant date is established. Total compensation expense for PeRSUs is determined by the product of the number of shares eligible to be awarded and expected to vest, and the market price of the Company’s common stock, commencing at the inception of the requisite service period. During the performance period, the compensation expense for PeRSUs is re-computed using the market price and the performance modifier at the end of a reporting period. At the end of the performance period, if the goals are attained, the awards are granted and classified as RSUs and accounted for on that basis. We recognize compensation expense for these awards on a straight-line basis over the requisite aggregate service period of generally four years.
TSRUs replace PeRSUs for our executive officers beginning in 2015. The number of vested TSRUs is assessed at the end of a three-year performance period and is conditioned upon attainment of a total shareholder return metric relative to a peer group of companies. We use the Monte Carlo simulation model to measure the fair value of TSRUs. TSRUs have a requisite service period of approximately 3 years. For TSRUs that are designated as equity awards, the fair value is measured at the grant date and expense is attributed to the requisite service period on a straight-line basis. For TSRUs that are eligible for cash settlement and designated as liability awards, we measure the fair value at the end of each reporting period and expense is recognized for services rendered based on the adjusted fair value of the awards. The weighted-average assumptions used to estimate the fair value of TSRUs included expected dividend yield of 0.5%, risk-free interest rate of 0.7%, expected stock volatility of 21.3% and contractual term of 3 years.
The following table summarizes restricted stock unit award activity during 2015:
(In millions, except per share data)	Shares		Weighted-
			Average
			Grant Date Fair
			Value Per Share
Nonvested, March 31, 2014	4		$	93.25
Granted	1		187.03
Vested	-1		84.28
Nonvested, March 31, 2015	4		$	129.57
The following table provides data related to restricted stock unit award activity:
	Years Ended March 31,
(In millions)	2015				2014				2013
Total fair value of shares vested	$	126			$	184			$	66
Total compensation cost, net of estimated forfeitures, related to nonvested restricted stock unit awards not yet recognized, pre-tax	$	206			$	236			$	210
Weighted-average period in years over which restricted stock unit award cost is expected to be recognized	2				2				2
Employee Stock Purchase Plan (“ESPP”)
The Company has an ESPP under which 21 million shares have been authorized for issuance. The ESPP allows eligible employees to purchase shares of our common stock through payroll deductions. The deductions occur over three-month purchase periods and the shares are then purchased at 85% of the market price at the end of each purchase period. Employees are allowed to terminate their participation in the ESPP at any time during the purchase period prior to the purchase of the shares. The 15% discount provided to employees on these shares is included in compensation expense. The shares related to funds outstanding at the end of a quarter are included in the calculation of diluted weighted average shares outstanding. These amounts have not been significant. Shares issued under the ESPP were not material in 2015 and 2014 and 1 million in 2013. At March 31, 2015, 5 million shares remain available for issuance.

Other_Income_Expense_Net

Other Income (Expense), Net	12 Months Ended
	Mar. 31, 2015
Other Nonoperating Income (Expense) [Abstract]
Other Income (Expense), Net	Other Income, Net
		Years Ended March 31,
	(In millions)	2015		2014		2013
	Interest income	$	20	$	16	$	22
	Equity in earnings (loss), net (1)	12		—		3
	Other, net (1)	31		16		9
	Total	$	63	$	32	$	34
	-1	Primarily recorded within our Distribution Solutions segment.

Income_Taxes

Income Taxes	12 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Income from continuing operations before income taxes
	U.S.	$	1,893		$	1,554		$	1,562
	Foreign	764			617			388
	Total income from continuing operations before income taxes	$	2,657		$	2,171		$	1,950
	Income tax expense related to continuing operations consists of the following:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Current
	Federal	$	453		$	484		$	(84	)
	State	90			64			14
	Foreign	101			193			46
	Total current	644			741			(24		)
	Deferred
	Federal	195			24			538
	State	53			10			80
	Foreign	(77		)	(18		)	(7		)
	Total deferred	171			16			611
	Income tax expense	$	815		$	757		$	587
	During 2015, 2014 and 2013, income tax expense related to continuing operations was $815 million, $757 million and $587 million and included net discrete tax benefit of $33 million, net discrete tax expense of $94 million and net discrete tax benefit of $29 million. Our discrete tax expense for 2014 is primarily related to a $122 million charge regarding an unfavorable decision from the Tax Court of Canada with respect to transfer pricing issues. The 2013 federal and state current income tax expense reflects the utilization of alternative minimum tax credit carryforwards.
	We have received reassessments from the Canada Revenue Agency (“CRA”) related to a transfer pricing matter impacting years 2003 through 2010, and have filed Notices of Appeal to the Tax Court of Canada for all of these years. On December 13, 2013, the Tax Court of Canada dismissed our appeal of the 2003 reassessment and we have filed a Notice of Appeal to the Federal Court of Appeal regarding this tax year. After the close of 2015, we reached an agreement in principle with the CRA to settle the transfer pricing matter for years 2003 through 2010. Since the agreement in principle did not occur within 2015, we have not reflected this potential settlement in our 2015 financial statements. We will record the final settlement amount in a subsequent quarter and do not expect it to have a material impact to income tax expense.
	During 2015, we reached an agreement with the Internal Revenue Service (“IRS”) to settle all outstanding issues relating to years 2003 through 2006 and recognized discrete tax benefits of $55 million to record previously unrecognized tax benefits and related interest.
	The IRS has been examining our U.S. corporation income tax returns for 2007 through 2009. We anticipate that they will issue a Revenue Agent Report in 2016 to disclose the results of their audit and any proposed assessments. The CRA is currently examining our Canadian income tax returns for years 2011 through 2013. In nearly all jurisdictions, the tax years prior to 2003 are no longer subject to examination.
	Significant judgments and estimates are required in determining the consolidated income tax provision and evaluating income tax uncertainties. Although our major taxing jurisdictions are the U.S. and Canada, we are subject to income taxes in numerous foreign jurisdictions. Our income tax expense, deferred tax assets and liabilities and uncertain tax liabilities reflect management’s best assessment of estimated current and future taxes to be paid. We believe that we have made adequate provision for all income tax uncertainties.
	The reconciliation between our effective tax rate on income from continuing operations and statutory tax rate is as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Income tax expense at federal statutory rate	$	930		$	760		$	683
	State income taxes net of federal tax benefit	81			57			58
	Foreign income taxed at various rates	(247		)	(177		)	(143		)
	Canadian litigation	—			122			—
	Controlled substance distribution reserve	58			—			—
	Unrecognized tax benefits and settlements	10			(6		)	1
	Tax credits	(10		)	(6		)	(13		)
	Other, net	(7		)	7			1
	Income tax expense	$	815		$	757		$	587
	At March 31, 2015, undistributed earnings of our foreign operations totaling $4,916 million were considered to be permanently reinvested. No deferred tax liability has been recognized on the basis difference created by such earnings since it is our intention to utilize those earnings in the foreign operations as well as to fund certain research and development activities for an indefinite period of time. The determination of the amount of deferred taxes on these earnings is not practicable because the computation would depend on a number of factors that cannot be known until a decision to repatriate the earnings is made.
	Deferred tax balances consisted of the following:
		March 31,
	(In millions)	2015			2014
	Assets
	Receivable allowances	$	83		$	94
	Deferred revenue	72			136
	Compensation and benefit related accruals	681			632
	Net operating loss and credit carryforwards	316			337
	Other	266			287
	Subtotal	1,418			1,486
	Less: valuation allowance	(229		)	(200		)
	Total assets	1,189			1,286
	Liabilities
	Inventory valuation and other assets	(2,333		)	(2,161		)
	Fixed assets and systems development costs	(324		)	(320		)
	Intangibles	(1,073		)	(1,477		)
	Other	(61		)	(117		)
	Total liabilities	(3,791		)	(4,075		)
	Net deferred tax liability	$	(2,602	)	$	(2,789	)
	Current net deferred tax asset	$	26		$	42
	Current net deferred tax liability	(1,819		)	(1,588		)
	Long-term deferred tax asset	50			19
	Long-term deferred tax liability	(859		)	(1,262		)
	Net deferred tax liability	$	(2,602	)	$	(2,789	)
	We assess the available positive and negative evidence to determine whether deferred tax assets are more likely than not to be realized.  As a result of this assessment, valuation allowances have been recorded on certain deferred tax assets in various tax jurisdictions.  The increase in valuation allowances in the current year relate primarily to net operating losses incurred in certain tax jurisdictions for which no tax benefit was recognized.
We have federal, state and foreign net operating loss carryforwards of $44 million, $1,930 million and $711 million. The federal and state net operating losses will expire at various dates from 2016 through 2035. Substantially all of our foreign net operating losses have indefinite lives.
The following table summarizes the activity related to our gross unrecognized tax benefits for the last three years:
	Years Ended March 31,
(In millions)	2015			2014			2013
Unrecognized tax benefits at beginning of period	$	647		$	560		$	595
Additions based on tax positions related to prior years	62			106			46
Reductions based on tax positions related to prior years	(18		)	(23		)	(106		)
Additions based on tax positions related to current year	27			23			31
Reductions based on settlements	(65		)	(4		)	(2		)
Reductions based on the lapse of the applicable statutes of limitations	(12		)	(7		)	(2		)
Exchange rate fluctuations	(25		)	(8		)	(2		)
Unrecognized tax benefits at end of period	$	616		$	647		$	560
Of the total $616 million in unrecognized tax benefits at March 31, 2015, $457 million would reduce income tax expense and the effective tax rate if recognized. During the next twelve months, it is reasonably possible that audit resolutions and the expiration of statutes of limitations could potentially reduce our unrecognized tax benefits by up to $137 million. However, this amount may change because we continue to have ongoing negotiations with various taxing authorities throughout the year.
We report interest and penalties on unrecognized tax benefits as income tax expense. In 2015 and 2014, we recognized an income tax benefit of $24 million and income tax expense of $48 million related to interest and penalties in our consolidated statements of operations. The income tax benefit for interest and penalties recognized in 2015 was primarily due to the lapses of statutes of limitations. The income tax expense for interest and penalties recognized in 2014 was primarily due to the additional interest resulting from the increase of our Canadian gross unrecognized tax benefits. At March 31, 2015 and 2014, we had $122 million and $179 million accrued for the payment of interest and penalties on unrecognized tax benefits.

Earnings_Per_Common_Share

Earnings Per Common Share	12 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share
	Basic earnings per common share attributable to McKesson are computed by dividing net income attributable to McKesson by the weighted average number of common shares outstanding during the reporting period. Diluted earnings per common share are computed similar to basic earnings per common share except that it reflects the potential dilution that could occur if dilutive securities or other obligations to issue common stock were exercised or converted into common stock.
	The computations for basic and diluted earnings per common share are as follows:
		Years Ended March 31,
	(In millions, except per share amounts)	2015			2014			2013
	Income from continuing operations	$	1,842		$	1,414		$	1,363
	Net loss (income) attributable to noncontrolling interests	(67		)	5			—
	Income from continuing operations attributable to McKesson	1,775			1,419			1,363
	Loss from discontinued operations, net of tax	(299		)	(156		)	(25		)
	Net income attributable to McKesson	$	1,476		$	1,263		$	1,338
	Weighted average common shares outstanding:
	Basic	232			229			235
	Effect of dilutive securities:
	Options to purchase common stock	1			1			1
	Restricted stock units	2			3			3
	Diluted	235			233			239
	Earnings (loss) per common share attributable to McKesson: (1)
	Diluted
	Continuing operations	$	7.54		$	6.08		$	5.69
	Discontinued operations	(1.27		)	(0.67		)	(0.10		)
	Total	$	6.27		$	5.41		$	5.59
	Basic
	Continuing operations	$	7.66		$	6.19		$	5.81
	Discontinued operations	(1.29		)	(0.68		)	(0.10		)
	Total	$	6.37		$	5.51		$	5.71
	-1	Certain computations may reflect rounding adjustments.
	Potentially dilutive securities include outstanding stock options, restricted stock units, and performance-based and other restricted stock units. Approximately 1 million, 2 million and 2 million of potentially dilutive securities were excluded from the computations of diluted net earnings per common share in 2015, 2014 and 2013, as they were anti-dilutive.

Receivables_Net

Receivables, Net	12 Months Ended
	Mar. 31, 2015
Receivables, Net, Current [Abstract]
Receivables, Net	Receivables, Net
		March 31,
	(In millions)	2015			2014
	Customer accounts	$	13,117		$	12,169
	Other	2,965			1,740
	Total	16,082			13,909
	Allowances	(168		)	(129		)
	Net	$	15,914		$	13,780
	Other receivables primarily include amounts due from suppliers and customer unbilled receivables. The allowances are primarily for estimated uncollectible accounts.

Property_Plant_and_Equipment_N

Property, Plant and Equipment, Net	12 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Net	Property, Plant and Equipment, Net
		March 31,
	(In millions)	2015			2014
	Land	$	207		$	221
	Building, machinery, equipment and other	3,237			3,155
	Total property, plant and equipment	3,444			3,376
	Accumulated depreciation	(1,399		)	(1,180		)
	Property, plant and equipment, net	$	2,045		$	2,196

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets, Net	12 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets, Net	Goodwill and Intangible Assets, Net
	Changes in the carrying amount of goodwill were as follows:
	(In millions)	Distribution				Technology				Total
		Solutions				Solutions
	Balance, March 31, 2013	$	4,413			$	1,992			$	6,405
	Goodwill acquired	3,649				—				3,649
	Amount reclassified to assets held-for-sale	(1		)		(127		)		(128		)
	Acquisition accounting, transfers and other adjustments	13				(12		)		1
	Foreign currency translation adjustments, net	4				(4		)		—
	Balance, March 31, 2014	$	8,078			$	1,849			$	9,927
	Goodwill acquired	93				—				93
	Amount reclassified to assets held-for-sale	(14		)		(1		)		(15		)
	Acquisition accounting, transfers and other adjustments	625				—				625
	Foreign currency translation adjustments, net	(788		)		(25		)		(813		)
	Balance, March 31, 2015	$	7,994			$	1,823			$	9,817
	As of March 31, 2015 and 2014, the accumulated goodwill impairment losses were $36 million in our Technology Solutions segment.
	Information regarding intangible assets is as follows:
		March 31, 2015												March 31, 2014
	(Dollars in millions)	Weighted		Gross				Accumulated				Net		Gross		Accumulated			Net
		Average		Carrying				Amortization				Carrying		Carrying		Amortization			Carrying
		Remaining		Amount								Amount		Amount					Amount
		Amortization
		Period
		(Years)
	Customer lists	8		$	2,683			$	(1,116	)		$	1,567	$	3,235	$	(863	)	$	2,372
	Service agreements	15		957				(215		)		742		995		(173		)	822
	Pharmacy licenses	26		874				(65		)		809		1,219		(11		)	1,208
	Trademarks and trade names	15		315				(82		)		233		367		(59		)	308
	Technology	3		213				(184		)		29		219		(173		)	46
	Other	4		162				(101		)		61		166		(51		)	115
	Total			$	5,204			$	(1,763	)		$	3,441	$	6,201	$	(1,330	)	$	4,871
	Amortization expense of intangible assets was $494 million, $319 million and $215 million for 2015, 2014 and 2013. Estimated annual amortization expense of intangible assets is as follows: $419 million, $389 million, $360 million, $332 million and $303 million for 2016 through 2020, and $1,638 million thereafter. All intangible assets were subject to amortization as of March 31, 2015 and 2014.

Capitalized_Software_Held_for_

Capitalized Software Held for Sale	12 Months Ended
	Mar. 31, 2015
Capitalized Computer Software, Net [Abstract]
Capitalized Software Held For Sale	Capitalized Software Held for Sale, Net
	Changes in the carrying amount of capitalized software held for sale, net, which is included in other assets in the consolidated balance sheets, were as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Balance, at beginning of period	$	103		$	126		$	144
	Amounts capitalized	34			40			49
	Amortization expense	(40		)	(50		)	(56		)
	Impairment charges	—			(12		)	(10		)
	Foreign currency translations adjustments, net	(6		)	(1		)	(1		)
	Balance, at end of period	$	91		$	103		$	126
	Additionally, third party royalty fees paid were $91 million, $91 million and $88 million during 2015, 2014 and 2013.

Debt_and_Financing_Activities

Debt and Financing Activities	12 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Debt and Financing Activities	Debt and Financing Activities
	Information regarding long-term debt is as follows:
		March 31,
	(In millions)	2015			2014
	Denominated in U.S. Dollars
	Floating Rate Notes due September 10, 2015	$	400		$	400
	0.95% Notes due December 4, 2015	500			499
	3.25% Notes due March 1, 2016	600			599
	5.70% Notes due March 1, 2017	500			500
	1.29% Notes due March 10, 2017	700			700
	1.40% Notes due March 15, 2018	499			499
	7.50% Notes due February 15, 2019	349			349
	2.28% Notes due March 15, 2019	1,100			1,100
	4.75% Notes due March 1, 2021	599			598
	2.70% Notes due December 15, 2022	400			400
	2.85% Notes due March 15, 2023	400			400
	3.80% Notes due March 15, 2024	1,100			1,100
	7.65% Debentures due March 1, 2027	175			175
	6.00% Notes due March 1, 2041	493			493
	4.88% Notes due March 15, 2044	800			800
	Other	26			27
	Denominated in Euro and other foreign currencies
	4.00% Bonds due October 18, 2016	388			507
	4.50% Bonds due April 26, 2017	563			737
	Promissory Notes	—			297
	Bank liabilities and other	117			166
	Total debt	9,709			10,346
	Less current portion	(1,529		)	(1,417		)
	Total long-term debt	$	8,180		$	8,929
	Long-Term Debt
	On March 5, 2014, we issued floating rate notes due September 10, 2015 in an aggregate principal amount of $400 million (“Floating Rate Notes”), 1.29% notes due March 10, 2017 in an aggregate principal amount of $700 million (“2017 Notes”), 2.28% notes due March 15, 2019 in an aggregate principal amount of $1,100 million (“2019 Notes”), 3.80% notes due March 15, 2024 in an aggregate principal amount of $1,100 million (“2024 Notes”) and 4.88% notes due March 15, 2044 in an aggregate principal amount of $800 million (“2044 Notes”). The Floating Rate Notes bear interest at a floating rate equal to the three-month London Interbank Offered Rate plus 0.40% (0.66% at March 31, 2015) with interest payable quarterly on March 10, June 10, September 10 and December 10 of each year. Interest on the 2017 Notes is payable on March 10 and September 10 of each year. Interest on the 2019 Notes, the 2024 Notes and the 2044 Notes is payable on March 15 and September 15 of each year. We utilized the net proceeds from the issuance of these notes (each note constitutes a “Series”) of $4,068 million, net of discounts and offering expenses, to repay the borrowings under our 2014 Bridge Loan, as further described below.
	On March 8, 2013, we issued 1.40% notes due March 15, 2018 in an aggregate principal amount of $500 million and 2.85% notes due March 15, 2023 in an aggregate principal amount of $400 million. Interest on these notes is payable on March 15 and September 15 of each year. We utilized the net proceeds from the issuance of these notes (each note constitutes a “Series”) of $891 million, net of discounts and offering expenses, to repay the borrowings under our 2013 Bridge Loan, as further described below.
	On December 4, 2012, we issued 0.95% notes due December 4, 2015 in an aggregate principal amount of $500 million (“2015 Notes”) and 2.70% notes due December 15, 2022 in an aggregate principal amount of $400 million (“2022 Notes”). Interest on the 2015 Notes is payable on June 4 and December 4 of each year and interest on the 2022 Notes is payable on June 15 and December 15 of each year. We utilized the net proceeds from the issuance of these notes (each note constitutes a “Series”) of $892 million, net of discounts and offering expenses, for general corporate purposes and replenishing working capital that was used to repay long-term debt that matured.
	Each Series constitutes an unsecured and unsubordinated obligation of the Company and ranks equally with all of the Company’s existing and, from time-to-time, future unsecured and unsubordinated indebtedness outstanding. Each Series is governed by materially similar indentures and officers’ certificate specifying certain terms of each Series. With the exception of the Floating Rate Notes, upon 30 days notice to holders of a Series, we may redeem that Series at any time prior to maturity, in whole or in part, for cash at redemption prices that include accrued and unpaid interest and a make-whole premium, as specified in the indenture and officers’ certificate relating to that Series. In the event of the occurrence of both (1) a change of control of the Company and (2) a downgrade of a Series below an investment grade rating by each of Fitch Ratings, Moody’s Investors Service, Inc. and Standard & Poor’s Ratings Services within a specified period, an offer must be made to purchase that Series from the holders at a price in cash equal to 101% of the then outstanding principal amount of that Series, plus accrued and unpaid interest to, but not including, the date of repurchase. The indenture and the related officers’ certificate for each Series, subject to the exceptions and in compliance with the conditions as applicable, specify that we may not incur liens, enter into sale and leaseback transactions or consolidate, merge or sell all or substantially all of our assets. The indentures also contain customary events of default provisions.
	We also have Euro-denominated corporate bonds consisting of 4.00% bonds due October 18, 2016 and 4.50% bonds due April 26, 2017. Interest on these bonds is due annually each year. At March 31, 2015 and 2014, $388 million and $507 million of the 4.00% bonds and $563 million and $737 million of the 4.50% bonds, for a total of $951 million and $1,244 million, were outstanding. At March 31, 2014, these bonds were classified within current liabilities as bondholders had the option to redeem the bonds at par value plus accrued interest. This redemption option expired during the first quarter of 2015 and the remaining bonds outstanding will mature according to their respective maturity dates. Accordingly, these bonds were reclassified as long-term debt effective in the first quarter of 2015.
	We also have a Euro-denominated term loan due December 15, 2019 with a current variable interest rate of 1.93%. At March 31, 2015 and 2014, the outstanding balance of the term loan was $89 million and $100 million. At March 31, 2014, we also had $297 million in Euro-denominated promissory notes outstanding which were all repaid during 2015.
	In 2014, we repaid our $350 million 6.50% Notes due February 15, 2014 and in 2013, we repaid our $500 million 5.25% Notes due March 1, 2013. In 2013, we also repaid the debt we assumed in connection with our acquisition of PSSI comprised of 6.375% Senior Notes due 2022 and 3.125% Senior Convertible Notes due 2014 for $643 million including accrued interest using cash on hand and borrowings under our 2013 Bridge Loan, as further described below.
	Scheduled future payments of long-term debt are $1,529 million in 2016, $1,619 million in 2017, $1,086 million in 2018, $1,474 million in 2019, $19 million in 2020 and $3,982 million thereafter.
	Senior Bridge Term Loan Facilities
	In connection with our acquisition of Celesio, in January 2014, we entered into a $5.5 billion 364‑day unsecured Senior Bridge Term Loan Agreement (the “2014 Bridge Loan”) under terms substantially similar to those in our existing revolving credit facility. On February 4, 2014, we borrowed $4,957 million under this facility with such proceeds and cash on hand used to fund the acquisition of Celesio. On March 10, 2014, we repaid $4,076 million of the 2014 Bridge Loan borrowings with funds obtained from the issuance of long-term debt. On March 11, 2014, we repaid the remaining balance of the 2014 Bridge Loan borrowings using funds drawn on our Accounts Receivable Sales Facility and cash on hand. On April 30, 2014, the commitments under the 2014 Bridge Loan automatically terminated upon the settlement of the tender offers for the remaining common shares of Celesio. During the time it was outstanding, the 2014 Bridge Loan borrowings bore interest at 1.39% per annum, based on the London Interbank Offered Rate plus a margin based on the Company’s credit rating. Interest expense for 2014 included a total of $46 million of fees related to the 2014 Bridge Loan and a bridge loan agreement entered into during the third quarter of 2014 in anticipation of an earlier acquisition of Celesio.
	In connection with our acquisition of PSSI, in December 2012, we entered into a $2.1 billion unsecured Senior Bridge Term Loan Agreement (“2013 Bridge Loan”). In February 2013, we reduced the 2013 Bridge Loan commitment to $900 million. On February 22, 2013, we borrowed $900 million under the 2013 Bridge Loan with such proceeds and cash on hand used to redeem the assumed debt from PSSI and pay the equity shareholders of PSSI. On March 8, 2013, we repaid the 2013 Bridge Loan borrowings with funds obtained from the issuance of long-term debt and the bridge loan agreement was subsequently terminated. During the time it was outstanding, the 2013 Bridge Loan borrowings bore interest at 1.20% per annum, based on the London Interbank Offered Rate plus a margin based on the Company’s credit rating. Interest expense for 2013 included $11 million of fees related to the 2013 Bridge Loan.
	Accounts Receivable Facilities
	In November 2014, we extended our existing Accounts Receivable Sales Facility (the “Facility”) for a two-year period under terms substantially similar to those previously in place. The committed balance of the Facility is $1.35 billion, although from time-to-time, the available amount of the Facility may be less than $1.35 billion based on accounts receivable concentration limits and other eligibility requirements. The Facility will expire in November 2016.
	In 2015, 2014 and 2013, we borrowed nil, $550 million and $1,325 million under the Facility and we repaid nil, $550 million and $1,725 million. At March 31, 2015 and 2014, there were no secured borrowings and related securitized accounts receivable outstanding under the Facility.
	The Facility contains requirements relating to the performance of the accounts receivable and covenants relating to the Company. If we do not comply with these covenants, our ability to use the Facility may be suspended and repayment of any outstanding balances under the Facility may be required. At March 31, 2015 and 2014, we were in compliance with all financial covenants.
	We also have Accounts Receivable Factoring Facilities (the “Factoring Facilities”) denominated in foreign currencies with a total committed balance of $169 million. Transactions under these facilities are accounted for as secured borrowings and have interest rates ranging from 0.85% to 1.26%. These facilities will expire through January 2016 and we may renew certain facilities before their expiration. During the 2015 and 2014, we borrowed $2,875 million and $570 million and repaid $2,908 million and $575 million in short-term borrowings under these facilities. At March 31, 2015 and 2014, there were $135 million and $246 million in secured borrowings and related accounts receivable outstanding under these facilities, which are included in short-term borrowings and receivables in our consolidated balance sheet.
	Revolving Credit Facilities and Lines of Credit
	We have a syndicated $1.3 billion five-year senior unsecured revolving credit facility, which expires in September 2016. Borrowings under this credit facility bear interest based upon either the London Interbank Offered Rate or a prime rate. There were no borrowings under this credit facility during 2015, 2014 and 2013. As of March 31, 2015 and 2014, there were no borrowings outstanding under this credit facility.
	We also have a syndicated €500 million five-year senior unsecured revolving credit facility, which expires in February 2018.  Borrowings under this facility bear interest based upon the Euro Interbank Offered Rate plus an agreed margin. During 2015 and 2014, there were no borrowings under this facility and no amounts outstanding as of March 31, 2015 and 2014.
	We also maintain bilateral credit lines primarily denominated in Euros with a total committed and uncommitted balance of $1.4 billion. These credit lines have interest rates ranging from 0.20% to 6.00% with interest payable monthly. During 2015, we borrowed $225 million and repaid $267 million under these credit lines primarily related to short‑term borrowings. Borrowings and repayments during 2014 were not material. As of March 31, 2015 and 2014, there were $29 million and $65 million outstanding under these credit lines.
	Commercial Paper: There were no commercial paper issuances during 2015, 2014 and 2013 and no amounts outstanding at March 31, 2015 and 2014.
	Debt Covenants: Our various borrowing facilities and long-term debt are subject to certain covenants. Our principal debt covenant is our debt to capital ratio under our $1.3 billion unsecured revolving credit facility, which cannot exceed 65%. For the purpose of calculating this ratio, borrowings under the $1.35 billion Accounts Receivable Sales Facility are excluded. If we exceed this ratio, repayment of debt outstanding under the revolving credit facility could be accelerated. As of March 31, 2015, we were in compliance with our financial covenants.

Variable_Interest_Entities

Variable Interest Entities	12 Months Ended
	Mar. 31, 2015
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entities	Variable Interest Entities
	We evaluate our ownership, contractual and other interests in entities to determine if they are variable interest entities (“VIEs”), if we have a variable interest in those entities and the nature and extent of those interests. These evaluations are highly complex and involve judgment and the use of estimates and assumptions based on available historical information and management’s judgment, among other factors. Based on our evaluations, if we determine we are the primary beneficiary of such VIEs, we consolidate such entities into our financial statements.
	Consolidated Variable Interest Entities
	We consolidate VIEs when we have the power to direct the activities that most significantly impact the VIE’s economic performance and the obligation to absorb losses or the right to receive benefits of the VIE and, as a result, are considered the primary beneficiary of the VIE. We consolidate certain single-lessee leasing entities where we, as the lessee, have the majority risk of the leased assets due to our minimum lease payment obligations to these leasing entities. As a result of absorbing this risk, the leases provide us with the power to direct the operations of the leased properties and the obligation to absorb losses or the right to receive benefits of the entity. Consolidated VIEs have an immaterial impact on our consolidated statements of operations and cash flows. Total assets and liabilities included in our consolidated balance sheet for these VIEs were $144 million and $51 million at March 31, 2015 and $160 million and $75 million at March 31, 2014.
	Investments in Unconsolidated Variable Interest Entities
	We are involved with VIEs which we do not consolidate because we do not have the power to direct the activities that most significantly impact their economic performance and thus are not considered the primary beneficiary of the entities. Our relationships include equity investments and lending, leasing, contractual or other relationships with the VIEs. Our most significant relationships are with oncology and other specialty practices. Under these practice arrangements, we generally own or lease all of the real estate and equipment used by the affiliated practices and manage the practices’ administrative functions. We also have relationships with certain pharmacies in Europe with whom we may provide financing, have equity ownership and/or a supply agreement whereby we supply the vast majority of the pharmacies’ purchases. Our maximum exposure to loss (regardless of probability) as a result of all unconsolidated VIEs was $1.2 billion at March 31, 2015 and 2014, which primarily represents the value of intangible assets related to service agreements and lease and loan receivables. These amounts exclude the customer loan guarantees discussed in Financial Note 22, “Financial Guarantees and Warranties.” We believe that there is no material loss exposure on these assets or from these relationships.

Pension_Benefits

Pension Benefits (Pension Plans Excluding Other Postretirement Benefit Plans [Member])	12 Months Ended
	Mar. 31, 2015
Pension Plans Excluding Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Benefits	Pension Benefits
	We maintain a number of qualified and nonqualified defined benefit pension plans and defined contribution plans for eligible employees.
	Defined Benefit Pension Plans
	Eligible U.S. employees who were employed by the Company as of December 31, 1995 are covered under the Company-sponsored defined benefit retirement plan. In 1997, the plan was amended to freeze all plan benefits as of December 31, 1996. Benefits for the defined benefit retirement plan are based primarily on age of employees at date of retirement, years of creditable service and the average of the highest 60 months of pay during the 15 years prior to the plan freeze date. We also have defined benefit pension plans for eligible employees outside of the U.S., as well as an unfunded nonqualified supplemental defined benefit plan for certain U.S. executives.
	Our non-U.S. defined benefit pension plans cover eligible employees located predominantly in Norway, United Kingdom and Germany. Benefits for these plans are based primarily on each employee’s final salary, with annual adjustments for inflation. The obligations in Norway are largely related to the state-regulated pension plan which is managed by the Norwegian Public Service Pension Fund (“SPK”). According to the terms of the SPK, the plan assets of state regulated plans in Norway must correspond very closely to the pension obligation calculated using the principles codified in Norwegian law. The shortfall may not exceed 1% of the obligation. If the shortfall exceeds this threshold, it must be remedied within two years. In the United Kingdom, we have subsidiaries that participate in a joint pension plan. This plan is largely funded by contractual trust arrangements that hold Company assets that may only be used to pay pension obligations. The Trustee Board decides on the minimum contribution to the plan in association with selected employees of the entity. A valuation is performed at regular intervals in order to determine the amount of the contribution and to ensure that the minimum contribution is made. The pension obligation in Germany is unfunded with the exception of the contractual trust arrangement used to fund pensions of Celesio’s Management Board.
	Defined benefit plan assets and obligations are measured as of the Company’s fiscal year-end.
	The net periodic expense for our pension plans, which includes net pension expense of Celesio beginning February 2014, is as follows:
		U.S. Plans											Non-U.S. Plans
		Years Ended March 31,											Years Ended March 31,
	(In millions)	2015				2014				2013			2015				2014			2013
	Service cost - benefits earned during the year	$	1			$	4			$	4		$	16			$	6		$	3
	Interest cost on projected benefit obligation	19				19				21			34				11			7
	Expected return on assets	(21		)		(20		)		(20		)	(30		)		(12		)	(8		)
	Amortization of unrecognized actuarial loss, prior service costs and net transitional obligation	19				32				28			3				4			4
	Curtailment/settlement loss (gain)	—				—				—			6				(1		)	—
	Net periodic pension expense	$	18			$	35			$	33		$	29			$	8		$	6
	The projected unit credit method is utilized in measuring net periodic pension expense over the employees’ service life for the pension plans. Unrecognized actuarial losses exceeding 10% of the greater of the projected benefit obligation or the market value of assets are amortized straight-line over the average remaining future service periods.
	Information regarding the changes in benefit obligations and plan assets for our pension plans is as follows:
		U.S. Plans								Non-U.S. Plans
		Years Ended March 31,								Years Ended March 31,
	(In millions)	2015				2014				2015			2014
	Change in benefit obligations
	Benefit obligation at beginning of period (1)	$	540			$	580			$	934		$	156
	Service cost	1				4				16			6
	Interest cost	19				19				34			11
	Actuarial loss (gain)	53				(24		)		194			15
	Benefit payments	(30		)		(30		)		(49		)	(12		)
	Amendments	—				(9		)		(6		)	—
	Acquisitions	—				—				—			740
	Foreign exchange impact and other	—				—				(160		)	18
	Benefit obligation at end of period (1)	$	583			$	540			$	963		$	934
	Change in plan assets
	Fair value of plan assets at beginning of period	$	300			$	290			$	590		$	135
	Actual return on plan assets	16				28				88			11
	Employer and participant contributions	12				12				73			12
	Benefits paid	(30		)		(30		)		(49		)	(10		)
	Acquisitions	—				—				—			426
	Foreign exchange impact and other	—				—				(90		)	16
	Fair value of plan assets at end of period	$	298			$	300			$	612		$	590
	Funded status at end of period	$	(285	)		$	(240	)		$	(351	)	$	(344	)
	Amounts recognized on the balance sheet
	Current liabilities	$	(17	)		$	(13	)		$	(6	)	$	(9	)
	Long-term liabilities	(268		)		(227		)		(345		)	(335		)
	Total	$	(285	)		$	(240	)		$	(351	)	$	(344	)
	-1	The benefit obligation is the projected benefit obligation.
	The following table provides the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for all our pension plans with an accumulated benefit obligation in excess of plan assets.
		U.S. Plans								Non-U.S. Plans
		March 31,								March 31,
	(In millions)	2015				2014				2015			2014
	Projected benefit obligation	$	583			$	540			$	963		$	934
	Accumulated benefit obligation	583				540				897			894
	Fair value of plan assets	298				300				612			590
	Amounts recognized in accumulated other comprehensive income (pre-tax) consist of:
		U.S. Plans								Non-U.S. Plans
		March 31,								March 31,
	(In millions)	2015				2014				2015			2014
	Net actuarial loss	$	220			$	188			$	175		$	71
	Prior service credit	—				(7		)		(6		)	—
	Total	$	220			$	181			$	169		$	71
	Other changes in accumulated other comprehensive income (pre-tax) were as follows:
		U.S. Plans											Non-U.S. Plans
		Years Ended March 31,											Years Ended March 31,
	(In millions)	2015				2014				2013			2015				2014			2013
	Net actuarial loss (gain)	$	58			$	(31	)		$	59		$	117			$	12		$	11
Prior service credit	—				(8		)		—			(8		)		—			—
Amortization of:
Net actuarial loss	(27		)		(32		)		(27		)	(5		)		(4		)	(4		)
Prior service credit (cost)	8				—				(1		)	2				2			—
Foreign exchange impact and other	—				(1		)		—			(8		)		4			(4		)
Total recognized in other comprehensive loss (income)	$	39			$	(72	)		$	31		$	98			$	14		$	3
We expect to amortize $1 million of prior service credit and $47 million of actuarial loss for the pension plans from stockholders’ equity to pension expense in 2016. Comparable 2015 amounts were $7 million of prior service credit and $31 million of actuarial loss.
Projected benefit obligations related to our unfunded U.S. plans were $189 million and $188 million at March 31, 2015 and 2014. Pension obligations for our unfunded plans are based on the recommendations of independent actuaries. Projected benefit obligations relating to our unfunded non-U.S. plans were $222 million and $260 million at March 31, 2015 and 2014. Funding obligations for our non-U.S. plans vary based on the laws of each non-U.S. jurisdiction.
Expected benefit payments, including assumed executive lump sum payments, for our pension plans are as follows: $74 million, $172 million, $75 million, $94 million and $66 million for 2016 to 2020 and $333 million for 2021 through 2025. Expected benefit payments are based on the same assumptions used to measure the benefit obligations and include estimated future employee service. Expected contributions to be made for our pension plans are $54 million for 2016.
Weighted-average assumptions used to estimate the net periodic pension expense and the actuarial present value of benefit obligations were as follows:
	U.S. Plans									Non-U.S. Plans
	Years Ended March 31,									Years Ended March 31,
	2015			2014			2013			2015		2014			2013
Net periodic pension expense
Discount rates	3.74	%		3.39	%		4.11	%		3.85	%	3.95	%		4.5	%
Rate of increase in compensation	4			4			4			3.11		2.66			3.1
Expected long-term rate of return on plan assets	7.25			7.25			7.25			5.39		5.71			6.13
Benefit obligation
Discount rates	3.18	%		3.58	%		3.4	%		2.5	%	3.92	%		4.1	%
Rate of increase in compensation	4			4			4			3.24		3.27			3.05
Our defined benefit pension plan liabilities are valued using a discount rate based on a yield curve developed from a portfolio of high quality corporate bonds rated AA or better whose maturities are aligned with the expected benefit payments of our plans. For March 31, 2015, our U.S. defined benefit liabilities are valued using a weighted average discount rate of 3.18%, which represents a decrease of 40 basis points from our 2014 weighted-average discount rate of 3.58%. Our non-U.S defined benefit pension plan liabilities are valued using a weighted-average discount rate of 2.50%, which represents a decrease of 142 basis points from our 2014 weighted-average discount rate of 3.92%.
Sensitivity to changes in the weighted-average discount rate for our pension plans is as follows:
	U.S. Plans						Non-U.S. Plans
(In millions)	One Percentage			One Percentage			One Percentage			One Percentage
	Point Increase			Point Decrease			Point Increase			Point Decrease
Increase (decrease) on projected benefit obligation	$	-41		$	48		$	-149		$	180
Increase (decrease) on net periodic pension cost		-3			4			-2			5
Plan Assets
Investment Strategy: The overall objective for U. S. pension plan assets is to generate long-term investment returns consistent with capital preservation and prudent investment practices, with a diversification of asset types and investment strategies. Periodic adjustments are made to provide liquidity for benefit payments and to rebalance plan assets to their target allocations.
The target allocations for U.S. plan assets at March 31, 2015 and 2014 are 50% equity investments, 45% fixed income investments including cash and cash equivalents and 5% real estate. Equity investments include common stock, preferred stock, and equity commingled funds. Fixed income investments include corporate bonds, government securities, mortgage-backed securities, asset-backed securities, other directly held fixed income investments, and fixed income commingled funds. The real estate investment is in a commingled real estate fund.
For both U.S. and non-U.S. plan assets, the investment strategies are subject to local regulations and the asset/liability profiles of the plans in each individual country. Plan assets of the non-U.S. plans are broadly invested in a manner appropriate to the nature and duration of the expected future retirement benefits payable under the plans. Plan assets are primarily invested in high-quality corporate and government bond funds and equity securities. Assets are properly diversified to avoid excessive reliance on any particular asset, issuer or group of undertakings so as to avoid accumulations of risk in the portfolio as a whole.
We develop the expected long-term rate of return assumption based on the projected performance of the asset classes in which plan assets are invested. The target asset allocation was determined based on the liability and risk tolerance characteristics of the plans and at times may be adjusted to achieve overall investment objectives.
Fair Value Measurements: The following tables represent our pension plan assets as of March 31, 2015 and 2014, using the fair value hierarchy by asset class. The fair value hierarchy has three levels based on the reliability of the inputs used to determine fair value. Level 1 refers to fair values determined based on unadjusted quoted prices in active markets for identical assets. Level 2 refers to fair values estimated using significant other observable inputs and Level 3 includes fair values estimated using significant unobservable inputs.
	U.S. Plans															Non-U.S. Plans
	March 31, 2015															March 31, 2015
(In millions)	Level 1				Level 2				Level 3			Total				Level 1			Level 2			Level 3		Total
Cash and cash equivalents	$	55			$	1			$	—		$	56			$	8		$	—		$	—	$	8
Equity securities:
Common and preferred stock	18				—				—			18				—			—			—		—
Equity commingled funds	—				138				—			138				7			149			—		156
Fixed income securities:
Government securities	—				14				—			14				26			53			—		79
Corporate bonds	—				14				—			14				—			13			—		13
Mortgage-backed securities	—				14				—			14				—			—			—		—
Asset-backed securities and other	—				26				—			26				—			—			—		—
Fixed income commingled funds	—				—				—			—				64			127			—		191
Other:
Real estate funds	—				—				18			18				—			—			26		26
Other commingled funds	—				—				—			—				—			13			—		13
Other	—				—				—			—				7			115			4		126
Total	$	73			$	207			$	18		$	298			$	112		$	470		$	30	$	612
	U.S. Plans															Non-U.S. Plans
	March 31, 2014															March 31, 2014
(In millions)	Level 1				Level 2				Level 3			Total				Level 1			Level 2			Level 3		Total
Cash and cash equivalents	$	8			$	—			$	—		$	8			$	7		$	—		$	—	$	7
Equity securities:
Common and preferred stock	19				—				—			19				—			—			—		—
Equity commingled funds	—				132				—			132				6			157			—		163
Fixed income securities:
Government securities	—				7				—			7				4			—			—		4
Corporate bonds	—				22				—			22				6			236			—		242
Mortgage-backed securities	—				10				—			10				—			—			—		—
Asset-backed securities and other	—				22				—			22				—			—			—		—
Fixed income commingled funds	—				63				—			63				—			45			—		45
Other:
Real estate funds	—				—				16			16				—			19			7		26
Other commingled funds	—				—				—			—				3			49			—		52
Other	—				—				—			—				—			46			5		51
Total	$	27			$	256			$	16		299				$	26		$	552		$	12	590
Receivables (1)												1												—
Total												$	300											$	590
-1	Represents pending trades at March 31, 2014.
Cash and cash equivalents - Cash and cash equivalents include short-term investment funds that maintain daily liquidity and aim to have constant unit values of $1.00. The funds invest in short-term fixed income securities and other securities with debt-like characteristics emphasizing short-term maturities and high credit quality. Directly held cash and cash equivalents are classified as Level 1 investments. Cash and cash equivalents include money market funds and other commingled funds, which have daily net asset values derived from the underlying securities; these are classified as Level 1 investments.
Common and preferred stock - This investment class consists of common and preferred shares issued by U.S. and non-U.S. corporations. Common shares are traded actively on exchanges and price quotes are readily available. Preferred shares may not be actively traded. Holdings of common shares are generally classified as Level 1 investments. Preferred shares are classified as Level 2 investments.
Equity commingled funds - Some equity investments are held in commingled funds, which have daily net asset values derived from quoted prices for the underlying securities in active markets; these are classified as Level 1 or Level 2 investments.
Fixed income securities - Government securities consist of bonds and debentures issued by central governments or federal agencies; corporate bonds consist of bonds and debentures issued by corporations; mortgage-backed securities consist of debt obligations secured by a mortgage or pool of mortgages; and asset-backed securities primarily consist of debt obligations secured by an asset or pool of assets other than mortgages. Inputs to the valuation methodology include quoted prices for similar assets in active markets, and inputs that are observable for the asset, either directly or indirectly, for substantially the full term of the asset. Multiple prices and price types are obtained from pricing vendors whenever possible, enabling cross-provider price validations. Fixed income securities are generally classified as Level 1 or Level 2 investments.
Fixed income commingled funds - Some fixed income investments are held in exchange traded or commingled funds, which have daily net asset values derived from the underlying securities; these are classified as Level 1 or 2 investments.
Real estate funds - The value of the real estate funds is reported by the fund manager and is based on a valuation of the underlying properties. Inputs used in the valuation include items such as cost, discounted future cash flows, independent appraisals and market based comparable data. The real estate funds are classified as Level 3 investments.
Other commingled funds - The other commingled funds are invested in equities, bonds, commodities, other alternative investments and cash and cash equivalents. These funds are valued based on the weekly net asset values derived from the quoted prices for the underlying securities in active markets and, for alternative investments, based on other valuation techniques. Other commingled funds are classified as Level 1 or Level 2 investments.
Other - At March 31, 2015, this includes $39 million of plan asset value relating to the SPK. In principle, the SPK is organized as a pay-as-you-go system guaranteed by the Norwegian government as it holds no Company-owned assets to back the pension liabilities. The Company pays a pension premium used to fund the plan, which is paid directly to the Norwegian government who establishes an account for each participating employer to keep track of the financial status of the plan, including managing the contributions and the payments. Further, the investment return credited to this account is determined annually by the SPK based on the performance of long-term government bonds.
The following table represents a reconciliation of Level 3 plan assets held during the years ended March 31, 2015 and 2014:
	U.S. Plans											Non-U.S. Plans
(In millions)	Real Estate				Other				Total			Real				Other			Total
	Funds											Estate
												Funds
Balance at March 31, 2013	$	14			$	—			$	14		$	5			$	—		$	5
Acquisitions	—				—				—			1				5			6
Unrealized gain on plan assets still held	2				—				2			1				—			1
Purchases, sales and settlements	—				—				—			—				—			—
Balance at March 31, 2014	$	16			$	—			$	16		$	7			$	5		$	12
Acquisitions	—				—				—			—				—			—
Unrealized gain on plan assets still held	2				—				2			1				—			1
Purchases, sales and settlements	—				—				—			18				(1		)	17
Balance at March 31, 2015	$	18			$	—			$	18		$	26			$	4		$	30
Multiemployer Plans
The Company contributes to a number of multiemployer pension plans under the terms of collective-bargaining agreements that cover union-represented employees in the U.S. In 2015, we also contributed to the Pensjonsordningen for Apoteketaten (“POA”), a mandatory multiemployer pension scheme for our pharmacy employees in Norway, managed by the association of Norwegian Pharmacies.
The risks of participating in these multiemployer plans are different from single-employer pension plans in the following aspects: (i) assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers; (ii) if a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers; and (iii) if the Company chooses to stop participating in some of its multiemployer plans, the Company may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability. Actions taken by other participating employers may lead to adverse changes in the financial condition of a multiemployer benefit plan and our withdrawal liability and contributions may increase.
Contributions and amounts accrued for U.S. Plans were not material for the years ended March 31, 2015, 2014, and 2013. Contributions to the POA for non-U.S. Plans exceeding 5% of total plan contributions were $24 million and $5 million in 2015 and 2014. Based on actuarial calculations, we estimate the funded status for our non-U.S. Plans to be approximately 65% as of March 31, 2015. No amounts were accrued for liability associated with the POA as we have no intention to withdraw from the plan.
Defined Contribution Plans
We have a contributory profit sharing investment plan (“PSIP”) for U.S. eligible employees. Eligible employees may contribute to the PSIP up to 75% of their eligible compensation on a pre-tax or post-tax basis not to exceed IRS limits. The Company makes matching contributions in an amount equal to 100% of the employee’s first 3% of pay contributed and 50% for the next 2% of pay contributed. The Company also may make an additional annual matching contribution for each plan year to enable participants to receive a full match based on their annual contribution. The Company also contributed to non-U.S. plans that are available in certain countries. Contribution expenses for the PSIP and non-U.S. plans were $103 million, $83 million and $65 million for the years ended March 31, 2015, 2014, and 2013.

Postretirement_Benefits

Postretirement Benefits (Other Postretirement Benefit Plan, Defined Benefit [Member])	12 Months Ended
	Mar. 31, 2015
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement Benefits	Postretirement Benefits
	We maintain a number of postretirement benefits, primarily consisting of healthcare and life insurance (“welfare”) benefits, for certain eligible U.S. employees. Eligible employees consist of those who retired before March 31, 1999 and those who retired after March 31, 1999, but were an active employee as of that date, after meeting other age-related criteria. We also provide postretirement benefits for certain U.S. executives. Defined benefit plan obligations are measured as of the Company’s fiscal year-end.
	The net periodic expense for our postretirement welfare benefits is as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Service cost - benefits earned during the year	$	1		$	2		$	2
	Interest cost on accumulated benefit obligation	5			5			6
	Amortization of unrecognized actuarial gain and prior service credit	(4		)	(1		)	(2		)
	Curtailment gain	—			(2		)	—
	Net periodic postretirement expense	$	2		$	4		$	6
	Information regarding the changes in benefit obligations for our postretirement welfare plans is as follows:
		Years Ended March 31,
	(In millions)	2015			2014
	Benefit obligation at beginning of period	$	119		$	131
	Service cost	1			2
	Interest cost	5			5
	Actuarial loss (gain)	5			(2		)
	Benefit payments	(12		)	(15		)
	Curtailment gain	—			(2		)
	Benefit obligation at end of period	$	118		$	119
	The components of the amount recognized in accumulated other comprehensive income for the Company’s other postretirement benefits at March 31, 2015 and 2014 were net actuarial losses of $1 million and gains of $8 million and net prior service credits of $1 million and $1 million. Other changes in benefit obligations recognized in other comprehensive income were net actuarial losses of $9 million in 2015 and gains of $2 million and $7 million in 2014 and 2013.
	We estimate that the amortization of the actuarial gain from stockholders’ equity to other postretirement expense in 2016 will be $1 million. Comparable 2015 amount was $4 million.
	Other postretirement benefits are funded as claims are paid. Expected benefit payments for our postretirement welfare benefit plans are as follows: $10 million annually for 2016 to 2020 and $44 million cumulatively for 2021 through 2025. Expected benefit payments are based on the same assumptions used to measure the benefit obligations and include estimated future employee service. Expected contributions to be made for our postretirement welfare benefit plans are $10 million for 2016.
	Weighted-average discount rates used to estimate postretirement welfare benefit expenses were 4.07%, 3.84% and 4.44% for 2015, 2014 and 2013. Weighted-average discount rates for the actuarial present value of benefit obligations were 3.61%, 4.08% and 3.84% for 2015, 2014 and 2013.
	Actuarial gain or loss for the postretirement welfare benefit plan is amortized to income or expense over a three-year period. The assumed healthcare cost trends used in measuring the accumulated postretirement benefit obligation were 6.75% and 7.00% for prescription drugs, 7.25/6.75% and 7.50/7.00% for ages pre-65/post-65 medical and 5.00% for dental in 2015 and 2014. For 2015, 2014 and 2013, a one-percentage-point increase or decrease in the assumed healthcare cost trend rate would not have a material impact on the postretirement benefit obligations.
	Pursuant to various collective bargaining agreements, we contribute to multiemployer health and welfare plans that cover union-represented employees. Our liability is limited to the contractual dollar obligations set forth by the collective bargaining agreements. Contributions to the plans and amounts accrued were not material for the years ended March 31, 2015, 2014, and 2013.

Hedging_Activities

Hedging Activities	12 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Hedging Activities	Hedging Activities
	In the normal course of business, we are exposed to interest rate changes and foreign currency fluctuations. At times, we limit these risks through the use of derivatives such as interest rate swaps and forward foreign exchange contracts. In accordance with our policy, derivatives are only used for hedging purposes. We do not use derivatives for trading or speculative purposes.
	Foreign currency rate risk
	The majority of our operations are conducted in U.S. dollars; however, certain assets and liabilities, revenues and expense and purchasing activities are incurred in and exposed to other currencies. We have certain foreign currency rate risk programs that manage the impact of foreign currency fluctuation. These programs are utilized on a transactional basis when we consider there to be a risk in fair value or volatility in cash flows. These programs reduce but do not entirely eliminate foreign currency rate risk.
	At March 31, 2015 and 2014, forward contracts to hedge the U.S. dollar against cash flows denominated in Canadian dollars with total notional values of $399 million and $463 million were designated for hedge accounting. These contracts will mature between March 2016 and March 2020. Changes in the fair values for contracts designated for hedge accounting are recorded to accumulated other comprehensive income and reclassified into earnings in the same period in which the hedged transaction affects earnings; losses reclassified into earnings for contracts designated for hedge accounting were not material in 2015, 2014 and 2013.
	We also have a number of forward contracts to primarily hedge the Euro against cash flows denominated in British pounds and other European currencies. At March 31, 2015 and 2014, the total notional value of these contracts was $1,755 million and $1,091 million. These contracts will mature from April 2015 to February 2016 and none of these contracts were designated for hedge accounting. Changes in the fair values for contracts not designated for hedge accounting are recorded directly to earnings and accordingly, net losses from the changes in the fair value of these contracts of $189 million were recorded within operating expenses in 2015 and were not material in 2014. However, the losses from these contracts are largely offset by changes in the value of the underlying intercompany foreign currency loans.
	Interest rate risk
	From time to time, we have entered into interest rate swaps to hedge the interest rate risk associated with variable rate debt. Interest rate swaps are used to modify the market risk exposures in connection with the variable rate debt to achieve primarily fixed rate interest expense. The interest rate swap transactions generally involve the exchange of floating or fixed interest payments. Our interest rate swaps that were outstanding at March 31, 2014 all matured during the first half of 2015. These contracts were not designated for hedge accounting and, accordingly, changes in the fair value of these swaps were recorded directly in earnings. At March 31, 2014, the total gross notional value of these contracts was $96 million. Amounts recorded to earnings were not material for 2015 and 2014.
	Information regarding the fair value of derivatives on a gross basis is as follows:
		Balance Sheet	31-Mar-15						31-Mar-14
		Caption	Fair Value of				U.S. Dollar Notional		Fair Value of				U.S Dollar Notional
			Derivative						Derivative
	(In millions)		Asset		Liability				Asset		Liability
	Derivatives designated for hedge accounting
	Foreign exchange	Prepaid expenses and other	$	14	$	—	$	76	$	4	$	—	$	64
	contracts (current)
	Foreign exchange	Other assets	53		—		323		27		—		399
	contracts (non-current)
	Total		$	67	$	—			$	31	$	—
	Derivatives not designated for hedge accounting
	Foreign exchange	Prepaid expenses and other	$	7	$	—	$	493	$	2	$	—	$	255
	contracts (current)
	Foreign exchange	Other accrued liabilities	—		79		1,262		—		13		836
	contracts (current)
	Interest rate swap contracts (current)	Other accrued liabilities	—		—		—		—		1		96
	Total		$	7	$	79			$	2	$	14
	Refer to Financial Note 20, “Fair Value Measurements,” for more information on these recurring fair value measurements.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements
	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The analysis of fair value is conducted by our accounting and finance personnel who organizationally report to the Chief Financial Officer. There is a three-level hierarchy that prioritizes the inputs used in determining fair value by their reliability and preferred use, as follows:
	Level 1 - Valuations based on quoted prices in active markets for identical assets or liabilities.
	Level 2 - Valuations based on quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data.
	Level 3 - Valuations based on inputs that are both significant to the fair value measurement and unobservable.
	At March 31, 2015 and 2014, the carrying amounts of cash, certain cash equivalents, restricted cash, receivables, drafts and accounts payable, short-term borrowings and other current liabilities approximated their estimated fair values because of the short maturity of these financial instruments.
	Our long-term debt and other financing arrangements are carried at amortized cost. The carrying amounts and estimated fair values of these liabilities were $9.7 billion and $10.4 billion at March 31, 2015 and $10.3 billion and $10.7 billion at March 31, 2014. The estimated fair values of our long-term debt and other financing were determined using quoted market prices in a less active market and other observable inputs from available market information, which are considered to be Level 2 inputs, and may not be representative of actual values that could have been realized or that will be realized in the future.
	Assets Measured at Fair Value on a Recurring Basis
	Our financial assets measured at fair value on a recurring basis consist of the following:
		March 31, 2015								March 31, 2014
	(In millions)	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
	Cash Equivalents
	Money market funds (1)	$	2,880	$	—	$	—	$	2,880	$	2,284	$	—	$	—	$	2,284
	Time deposits (2)	—		94		—		94		—		12		—		12
	Repurchase agreements (2)	1,243		—		—		1,243		569		—		—		569
	Total cash equivalents	$	4,123	$	94	$	—	$	4,217	$	2,853	$	12	$	—	$	2,865
	(1) Gross unrealized gain and losses were not material for the years ended March 31, 2015 and 2014 based on quoted prices of identical investments.
	(2) The carrying amounts of these cash equivalents approximated their estimated fair values because of their short maturities.
	Fair values of our marketable securities were determined using quoted prices in active markets for identical assets, which are considered Level 1 inputs under the fair value measurements and disclosure guidance. Fair values for our marketable securities were not material at March 31, 2015 and 2014.
	Fair values of our forward foreign currency derivatives were determined using quoted market prices of similar instruments in an active market and other observable inputs from available market information.  These inputs are considered Level 2 under the fair value measurements and disclosure guidance, and may not be representative of actual values that could have been realized or that will be realized in the future. Refer to Financial Note 19, “Hedging Activities,” for more information on our forward foreign currency derivatives.
	There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the years ended March 31, 2015 and 2014.
	Assets Measured at Fair Value on a Nonrecurring Basis
	We measure certain long-lived assets at fair value on a nonrecurring basis when they are deemed to be other-than-temporarily impaired. If the cost of an investment exceeds its fair value, we evaluate, among other factors, our intent to hold the investment, general market conditions, the duration and extent to which the fair value is less than cost and the financial outlook for the industry and location. An impairment charge is recorded when the cost of the asset exceeds its fair value and this condition is determined to be other-than-temporary.
	Fiscal 2015
	As discussed in Financial Note 4, “Discontinued Operations,” during the fourth quarter of 2015, we recorded a $241 million pre-tax ($235 million after-tax) non-cash impairment charge to reduce the carrying value of our Brazilian distribution business to its estimated fair value, less cost to sell. The fair value of this business was determined using income and market valuation approaches. Under the income approach, we used a discounted cash flow (“DCF”) analysis based on the estimated future results. This valuation approach is considered a Level 3 fair value measurement due to the use of significant unobservable inputs related to the timing and amount of future cash flows based on projections of revenues and operating costs and discounting those cash flows to their present value. The key inputs and assumptions of the DCF method are the projected cash flows, the terminal value of the business and the discount rate. Under the market approach, we apply valuation multiples of reasonably similar publicly traded companies to the operating data of the subject business to derive the estimated fair value. This valuation approach is also considered a Level 3 fair value measurement. The key inputs for the market valuation approach were revenues and a selection of market multiples. The ultimate loss from the sale of the business may be higher or lower than our current assessment of the business’ fair value.
	Fiscal 2014
	As discussed in Financial Note 4, “Discontinued Operations,” during 2014, we recorded an $80 million non-cash pre-tax and after-tax impairment charge to reduce the carrying value of our International Technology business to its estimated fair value, less costs to sell. The impairment charge was primarily the result of the terms of the preliminary purchase offers received for this business during 2014. Accordingly, the fair value measurement is classified as Level 3 in the fair value hierarchy.
	Fiscal 2013
	As discussed in Financial Note 6, “Equity Investments,” during 2013, we committed to a plan to sell our investment in Nadro and, in the fourth quarter of 2013, recorded an impairment charge of $191 million to reduce the carrying value to fair value. The fair value of our investment in Nadro was determined using income and market valuation approaches. Under the income approach, we used a discounted cash flow (“DCF”) analysis based on estimated future results. This valuation approach is considered a Level 3 fair value measurement. The key inputs for the market valuation approach were Nadro’s fiscal 2012 unaudited earnings before interest, depreciation and amortization (“EBITDA”) and an EBITDA multiple based on similar guideline U.S. pharmaceutical companies whose securities are actively traded in public markets. This valuation approach is considered a Level 3 fair value measurement. Finally, we evaluated the fair values under both valuation methods and concluded on an average of the two methods. In September 2013, we completed the sale of our 49% interest in Nadro which resulted in no material gain or loss.
	As discussed in Financial Note 5, “Asset Impairments and Product Alignment Charges,” in 2013, we recorded a goodwill impairment charge of $36 million in one of Technology Solutions segment’s reporting units. The impairment charge was primarily the result of a significant decrease in estimated revenues for a software product. As required under step two of goodwill impairment testing, we determined the fair value of the reporting unit and the fair value of the reporting units’ net assets, excluding goodwill but including any unrecognized intangible assets. The implied fair value of goodwill was then calculated on a residual basis – that is, by subtracting the sum of the fair value of the net assets from the fair value of the reporting unit. The impairment was equal to the carrying amount of goodwill.
	Fair value assessment of the reporting unit as well as the reporting unit’s net assets are considered a Level 3 measurement due to the significance of unobservable inputs developed using company specific information. We used the market approach and income approach (DCF model) to determine the fair value of the reporting unit and a DCF model to determine the fair value of the reporting unit’s most significant assets – intangibles.

Lease_Obligations

Lease Obligations	12 Months Ended
	Mar. 31, 2015
Leases, Operating [Abstract]
Lease Obligations	Lease Obligations
	We lease facilities and equipment almost solely under operating leases. At March 31, 2015, future minimum lease payments required under operating leases that have initial or remaining noncancelable lease terms in excess of one year for years ending March 31 are:
	(In millions)	Noncancelable
		Operating
		Leases
	2016	$	316
	2017	271
	2018	219
	2019	170
	2020	140
	Thereafter	650
	Total minimum lease payments (1)	$	1,766
	-1	Minimum lease payments have not been reduced by minimum sublease rentals of $46 million due under future noncancelable subleases.
	Rental expense under operating leases was $440 million, $298 million and $232 million in 2015, 2014 and 2013. We recognize rent expense on a straight-line basis over the term of the lease, taking into account, when applicable, lessor incentives for tenant improvements, periods where no rent payment is required and escalations in rent payments over the term of the lease. Deferred rent is recognized for the difference between the rent expense recognized on a straight-line basis and the payments made per the terms of the lease. Remaining terms for facilities leases generally range from one to twelve years, while remaining terms for equipment leases range from one to five years. Most real property leases contain renewal options (generally for five-year increments) and provisions requiring us to pay property taxes and operating expenses in excess of base period amounts. Sublease rental income was not material for 2015, 2014 and 2013.

Financial_Guarantees_and_Warra

Financial Guarantees and Warranties	12 Months Ended
	Mar. 31, 2015
Financial Guarantees And Warranties [Abstract]
Financial Guarantees And Warranties	Financial Guarantees and Warranties
	Financial Guarantees
	We have agreements with certain of our customers’ financial institutions, mainly in Canada and Europe, under which we have guaranteed the repurchase of our customers’ inventory or our customers’ debt in the event these customers are unable to meet their obligations to those financial institutions. For our inventory repurchase agreements, among other requirements, inventories must be in resalable condition and any repurchase would be at a discount. The inventory repurchase agreements mostly relate to certain Canadian customers and generally range from one to two years. Customers’ debt guarantees range from one to fifteen years and are primarily provided to facilitate financing for certain customers. The majority of our customers’ debt guarantees are secured by certain assets of the customer. At March 31, 2015, the maximum amounts of inventory repurchase guarantees and customers’ debt guarantees were $185 million and $183 million, of which $1 million had been accrued. The expirations of these financial guarantees are as follows: $137 million, $42 million, $16 million, $21 million and $25 million from 2016 through 2020 and $127 million thereafter.
	At March 31, 2015, our banks and insurance companies have issued $142 million of standby letters of credit and surety bonds, which were issued on our behalf mostly related to our customer contracts and in order to meet the security requirements for statutory licenses and permits, court and fiduciary obligations and our workers’ compensation and automotive liability programs. Additionally, at March 31, 2015, we have a commitment to contribute up to $16 million to a non-consolidated investment for building and equipment construction.
	Our software license agreements generally include certain provisions for indemnifying customers against liabilities if our software products infringe a third party’s intellectual property rights. To date, we have not incurred any material costs as a result of such indemnification agreements and have not accrued any liabilities related to such obligations.
	In conjunction with certain transactions, primarily divestitures, we may provide routine indemnification agreements (such as retention of previously existing environmental, tax and employee liabilities) whose terms vary in duration and often are not explicitly defined. Where appropriate, obligations for such indemnifications are recorded as liabilities. Because the amounts of these indemnification obligations often are not explicitly stated, the overall maximum amount of these commitments cannot be reasonably estimated. Other than obligations recorded as liabilities at the time of divestiture, we have historically not made material payments as a result of these indemnification provisions.
	Warranties
	In the normal course of business, we provide certain warranties and indemnification protection for our products and services. For example, we provide warranties that the pharmaceutical and medical-surgical products we distribute are in compliance with the U.S. Food, Drug and Cosmetic Act and other applicable laws and regulations. We have received the same warranties from our suppliers, which customarily are the manufacturers of the products. In addition, we have indemnity obligations to our customers for these products, which have also been provided to us from our suppliers, either through express agreement or by operation of law.
	We also provide warranties regarding the performance of software and products we sell. Our liability under these warranties is to bring the product into compliance with previously agreed upon specifications. For software products, this may result in additional project costs, which are reflected in our estimates used for the percentage-of-completion method of accounting for software installation services within these contracts. In addition, most of our customers who purchase our software and automation products also purchase annual maintenance agreements. Revenues from these maintenance agreements are recognized on a straight-line basis over the contract period and the cost of servicing product warranties is charged to expense when claims become estimable. Accrued warranty costs were not material to the consolidated balance sheets.

Other_Commitments_and_Continge

Other Commitments and Contingent Liabilities	12 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Other Commitments and Contingent Liabilities	Other Commitments and Contingent Liabilities
	In addition to commitments and obligations in the ordinary course of business, we are subject to various claims, other pending and potential legal actions for damages, investigations relating to governmental laws and regulations and other matters arising out of the normal conduct of our business. As described below, many of these proceedings are at preliminary stages and many seek an indeterminate amount of damages.
	When a loss is considered probable and reasonably estimable, we record a liability in the amount of our best estimate for the ultimate loss. However, the likelihood of a loss with respect to a particular contingency is often difficult to predict and determining a meaningful estimate of the loss or a range of loss may not be practicable based on the information available and the potential effect of future events and decisions by third parties that will determine the ultimate resolution of the contingency. Moreover, it is not uncommon for such matters to be resolved over many years, during which time relevant developments and new information must be reevaluated at least quarterly to determine both the likelihood of potential loss and whether it is possible to reasonably estimate a range of possible loss. When a loss is probable but a reasonable estimate cannot be made, disclosure of the proceeding is provided.
	Disclosure also is provided when it is reasonably possible that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the recorded provision. We review all contingencies at least quarterly to determine whether the likelihood of loss has changed and to assess whether a reasonable estimate of the loss or range of loss can be made. As discussed above, development of a meaningful estimate of loss or a range of potential loss is complex when the outcome is directly dependent on negotiations with or decisions by third parties, such as regulatory agencies, the court system and other interested parties. Such factors bear directly on whether it is possible to reasonably estimate a range of potential loss and boundaries of high and low estimates.
	We are party to the legal proceedings described below. Unless otherwise stated, we are currently unable to estimate a range of reasonably possible losses for the unresolved proceedings described below. Should any one or a combination of more than one of these proceedings be successful, or should we determine to settle any or a combination of these matters, we may be required to pay substantial sums, become subject to the entry of an injunction or be forced to change the manner in which we operate our business, which could have a material adverse impact on our financial position or results of operations.
	I. Litigation and Claims
	On August 29, 2007, PSKW, LLC filed a lawsuit against McKesson Specialty Arizona Inc. in the New York Supreme Court, New York County, alleging that McKesson Specialty Arizona misappropriated trade secrets and confidential information in launching its LoyaltyScript® program, PSKW, LLC V. McKesson Specialty Arizona Inc., Index No. 602921/07.  Plaintiff later amended its complaint twice to add additional, but related claims. On August 31, 2011, McKesson Specialty Arizona moved for summary judgment on all claims.  On December 23, 2013, the court dismissed PSKW’s cause of action for misappropriation of ideas.  PSKW appealed this decision and on October 21, 2014, the Appellate Division reversed.  On January 30, 2015, the trial court granted McKesson Specialty Arizona’s motion to strike the jury and later set trial for June 15, 2015.
	On April 16, 2013, the Company’s wholly-owned subsidiary, U.S. Oncology, Inc. (“USON”), was served with a third amended qui tam complaint filed in the United States District Court for the Eastern District of New York by two relators, purportedly on behalf of the United States, twenty-one states and the District of Columbia, against USON and five other defendants, alleging that USON solicited and received illegal “kickbacks” from Amgen in violation of the Anti-Kickback Statute, the False Claims Act, and various state false claims statutes, and seeking damages, treble damages, civil penalties, attorneys’ fees and costs of suit, all in unspecified amounts, United States ex rel. Piacentile v. Amgen Inc., et al., CV 04-3983 (SJ). Previously, the United States declined to intervene in the case as to all allegations and defendants except for Amgen. On February 5, 2013, the United States filed a motion to dismiss the claims pled against Amgen. On September 30, 2013, the court granted the United States’ motion to dismiss. On April 4, 2014, USON filed a motion to dismiss the claims pled against it. The court has not yet ruled on USON’s motion.
	On June 17, 2014, U.S. Oncology Specialty, LP (“USOS”) was served with a fifth amended qui tam complaint filed in July 2008 in the United States District Court for the Eastern District of New York by a relator against USOS, among others, alleging that USOS solicited and received illegal “kickbacks” from Amgen in violation of the Anti-Kickbacks Statute, the False Claims Act, and various state false claims statutes, and seeking damages, treble damages, civil penalties, attorneys’ fees and costs of suit, all in unspecified amounts, United States ex rel. Hanks v. Amgen, Inc., et al., CV-08-03096 (SJ). Previously, the United States declined to intervene in the case as to all allegations and defendants except for Amgen. On August 1, 2014, USOS filed a motion to dismiss the claims pled against it and the hearing occurred on October 7, 2014. The court has not yet ruled on USOS’s motion.
	On May 21, 2014, four hedge funds managed by Magnetar Capital filed a complaint against McKesson Deutschland GmbH & Co. KGaA (formerly known as “Dragonfly GmbH & Co. KGaA”) (“Dragonfly”), a wholly‑owned subsidiary of the Company, in a German court in Frankfurt, Germany, alleging that Dragonfly violated German takeover law in connection with the Company’s acquisition of Celesio by paying more to some holders of Celesio’s convertible bonds than it paid to the shareholders of Celesio’s stock, Magnetar Capital Master Fund Ltd. et al. v. Dragonfly GmbH & Co KGaA, No. 3-05 O 44/14.  On December 5, 2014, the court fully dismissed Magnetar’s lawsuit in Dragonfly’s favor and ruled that the plaintiffs must bear the court costs and Dragonfly’s taxable lawyers’ fees. Magnetar filed a notice of appeal on January 5, 2015.
	II. Government Subpoenas and Investigations
	From time-to-time, the Company receives subpoenas or requests for information from various government agencies. The Company generally responds to such subpoenas and requests in a cooperative, thorough and timely manner. These responses sometimes require time and effort and can result in considerable costs being incurred by the Company. Such subpoenas and requests also can lead to the assertion of claims or the commencement of civil or criminal legal proceedings against the Company and other members of the health care industry, as well as to settlements. An example is the subpoena from the office of the Attorney General of West Virginia in the fourth quarter of 2015 seeking information about the Company’s distribution of controlled substances in West Virginia. The Company has provided the requested documents.
	In addition, in the fourth quarter of 2015, the Company reached an agreement in principle with the Drug Enforcement Administration (“DEA”), Department of Justice (“DOJ”) and various U.S. Attorney’s offices to settle all potential administrative and civil claims relating to investigations about the Company’s suspicious order reporting practices for controlled substances. The global settlement with the DEA and DOJ is subject to the execution of final settlement agreements. Under the terms of the agreement in principle, the Company has agreed to pay the sum of $150 million, implement certain remedial measures and have the following distribution centers’ DEA registrations suspended for the specified products and time periods: Aurora, Colorado: all controlled substances for three years; Livonia, Michigan: all controlled substances for two years; Washington Courthouse, Ohio: all controlled substances for the two-year period following completion of the Livonia suspension; and Lakeland, Florida: hydromorphone products for one year. Throughout the terms of these suspensions, the Company will be permitted to continue to ship controlled substances from its Livonia, Washington Courthouse and Lakeland distribution centers to customers that purchase products under its pharmaceutical prime vendor contract with the Department of Veterans Affairs. The Company expects that the suspensions will not result in a supply disruption to any customer. Customers located in the distribution center service areas described above will receive controlled substances from a different distribution center during the applicable suspension periods. As a result of our agreement in principle, during the fourth quarter of 2015, we recorded a $150 million pre-tax and after-tax charge relating to these claims.
	III. Environmental Matters
	Primarily as a result of the operation of the Company’s former chemical businesses, which were fully divested by 1987, the Company is involved in various matters pursuant to environmental laws and regulations. The Company has received claims and demands from governmental agencies relating to investigative and remedial actions purportedly required to address environmental conditions alleged to exist at six sites where it, or entities acquired by it, formerly conducted operations and the Company, by administrative order or otherwise, has agreed to take certain actions at those sites, including soil and groundwater remediation. In addition, the Company is one of multiple recipients of a New Jersey Department of Environmental Protection Agency directive and a separate United States Environmental Protection Agency directive relating to potential natural resources damages (“NRD”) associated with one of these six sites. Although the Company’s potential allocation under either directive cannot be determined at this time, it has agreed to participate with a potentially responsible party (“PRP”) group in the funding of certain tasks to support an NRD assessment, the costs of which are reflected in the aggregate estimates set forth below.
	Based on a determination by the Company’s environmental staff, in consultation with outside environmental specialists and counsel, the current estimate of the Company’s probable loss associated with the remediation costs for these six sites is $7 million, net of amounts anticipated from third parties. The $7 million is expected to be paid out between April 2015 and March 2035. The Company’s estimated probable loss for these environmental matters has been entirely accrued for in the accompanying consolidated balance sheets.
	In addition, the Company has been designated as a PRP under the Superfund law for environmental assessment and cleanup costs as the result of its alleged disposal of hazardous substances at 14 sites. With respect to these sites, numerous other PRPs have similarly been designated and while the current state of the law potentially imposes joint and several liability upon PRPs, as a practical matter, costs of these sites are typically shared with other PRPs. At one of these sites, the United States Environmental Protection Agency has selected a preferred remedy with an estimated cost of approximately $70 million. It is not certain at this point in time what proportion of this estimated liability will be borne by the Company or by the other PRPs. Accordingly, the Company’s estimated probable loss at those 14 sites is approximately $22 million, which has been entirely accrued for in the accompanying consolidated balance sheets. However, it is possible that the ultimate costs of these matters may exceed or be less than the reserves.
	IV. Value Added Tax Assessments
	We operate in various countries outside the United States which collect value added taxes (“VAT”).  The determination of the manner in which a VAT applies to our foreign operations is subject to varying interpretations arising from the complex nature of the tax laws. We have received assessments for VAT which are in various stages of appeal. We disagree with these assessments and believe that we have strong legal arguments to defend our tax positions.  Certain VAT assessments relate to years covered by an indemnification agreement.  Due to the complex nature of the tax laws, it is not possible to estimate the outcome of these matters.  However, based on the currently available information, we believe the ultimate outcome of these matters will not have a material adverse effect on our financial position, cash flows or results of operations.
	V. Average Wholesale Price (“AWP”) Litigation
	The Company has a reserve relating to AWP public entity claims, which is reviewed at least quarterly and whenever events or circumstances indicate changes. We recorded nil, $68 million and $72 million of pre-tax charges relating to changes in the Company’s AWP litigation reserve, including accrued interest, in 2015, 2014 and 2013. All charges were recorded in operating expenses within our Distribution Solutions segment. Cash payments of nil, $105 million and $483 million were made in 2015, 2014 and 2013. At March 31, 2015, the reserve for this matter was not material; at March 31, 2014, the reserve was $42 million.
	VI. Other Matters
	The Company is involved in various other litigation and governmental proceedings, not described above, that arise in the normal course of business. While it is not possible to determine the ultimate outcome or the duration of any such litigation or governmental proceedings, the Company believes, based on current knowledge and the advice of counsel, that such litigation and proceedings will not have a material impact on the Company’s financial position or results of operations.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity
	Each share of the Company’s outstanding common stock is permitted one vote on proposals presented to stockholders and is entitled to share equally in any dividends declared by the Company’s Board of Directors (the “Board”).
	In July 2013, the quarterly dividend was raised from $0.20 to $0.24 per common share for dividends declared after such date, until further action by the Board. Dividends were $0.96 per share in 2015, $0.92 per share in 2014 and $0.80 per share in 2013. The Company anticipates that it will continue to pay quarterly cash dividends in the future.  However, the payment and amount of future dividends remain within the discretion of the Board and will depend upon the Company’s future earnings, financial condition, capital requirements and other factors.
	Share Repurchase Plans
	Stock repurchases may be made from time-to-time in open market transactions, privately negotiated transactions, through accelerated share repurchase (“ASR”) programs, or by any combination of such methods. The timing of any repurchases and the actual number of shares repurchased will depend on a variety of factors, including our stock price, corporate and regulatory requirements, restrictions under our debt obligations and other market and economic conditions.
	Information regarding the share repurchase activity over the last three years is as follows:
		Share Repurchases (1)
	(In millions, except price per share data)		Total		Average Price				Approximate
			Number of		Paid Per Share				Dollar Value of
			Shares						Shares that May
			Purchased (2) (3)						Yet Be Purchased
									Under the
									Programs
	Balance, March 31, 2012								$	299
	Share repurchase plans approved:
	Apr-12								700
	Jan-13								500
	Shares repurchased		13		$	100.82			(1,159		)
	Balance, March 31, 2013								$	340
	Shares repurchased		—		$	—			—
	Balance, March 31, 2014								$	340
	Shares repurchased		1.5		$	226.55			(340		)
	Balance, March 31, 2015								$	—
	-1	This table does not include shares tendered to satisfy the exercise price in connection with cashless exercises of employee stock options or shares tendered to satisfy tax withholding obligations in connection with employee equity awards.
	-2	All of the shares purchased were part of the publicly announced programs.
	-3	The number of shares purchased reflects rounding adjustments.
	In May 2015, the Board authorized the repurchase of up to $500 million of the Company’s common stock.
	During the fourth quarter of 2013, we retired approximately 2 million shares that were repurchased for $217 million by the Company.   The retired shares constitute authorized but unissued shares. We elected to allocate any excess of share repurchase price over par value between additional paid-in capital and retained earnings. As such, $195 million was recorded as a decrease to retained earnings.
	Other Comprehensive Income (Loss)
	Information regarding other comprehensive income (loss) including noncontrolling and redeemable noncontrolling interests, net of tax, by component is as follows:
		Years Ended March 31,
	(In millions)	2015				2014				2013
	Foreign currency translation adjustments
	Foreign currency translation adjustments arising during period, net of income tax expense (benefit) of nil, nil and ($2) (1)	$	(1,845	)		$	9			$	(52	)
	Reclassified to income statement, net of income tax expense of nil, $24 and nil (2)	(10		)		44				—
		(1,855		)		53				(52		)
	Unrealized losses on cash flow hedges
	Unrealized losses on cash flow hedges arising during period, net of income tax benefit of nil, nil and nil	(13		)		(6		)		—
	Reclassified to income statement, net of income tax expense of nil, nil and nil	3				—				—
		(10		)		(6		)		—
	Changes in retirement-related benefit plans
	Net actuarial gain (loss) and prior service credit (cost) arising during period, net of income tax (benefit) of ($66), $16 and ($22)	(140		)		17				(40		)
	Amortization of actuarial loss, prior service cost and transition obligation, net of income tax expense of $6, $12 and $12 (3)	11				22				18
	Foreign currency translation adjustments and other, net of income tax expense of nil, nil and nil	4				(4		)		4
	Reclassified to income statement, net of income tax expense of nil, $1 and nil	1				1				—
		(124		)		36				(18		)
	Other Comprehensive Income (Loss), net of tax	$	(1,989	)		$	83			$	(70	)
	-1	2015 includes net foreign currency translation losses of $267 million and 2014 includes net foreign currency translations gains of $21 million attributable to noncontrolling and redeemable noncontrolling interests.
	-2	2014 includes net foreign currency translation losses of $44 million reclassified from accumulated other comprehensive income to other income (loss), net, within our consolidated statement of operations due to the sale of our 49% equity interest in Nadro. Such losses were previously considered in our impairment evaluation of the investment when we committed to a plan to sell the investment during the fourth quarter of 2013 and, accordingly, did not impact earnings in 2014.
	-3	Pre-tax amount was reclassified into cost of sales and operating expenses in the consolidated statements of operations. The related tax expense was reclassified into income tax expense in the consolidated statements of operations.
	Accumulated Other Comprehensive Income (Loss)
	Information regarding changes in our accumulated other comprehensive income (loss) by component are as follows:
	(In millions)	Foreign Currency Translation Adjustments, Net of Tax				Unrealized Losses on Cash Flow Hedges,				Unrealized Net Gains (Losses) and Other Components of Benefit Plans, Net of Tax			Total Accumulated Other Comprehensive Income (Loss)
						Net of Tax
	Balance at March 31, 2013	$	136			$	(5	)		$	(196	)	$	(65	)
	Other comprehensive income (loss) before reclassifications	9				(6		)		35			38
	Amounts reclassified to earnings	44				—				1			45
	Other comprehensive income (loss)	$	53			$	(6	)		$	36		$	83
	Less: other comprehensive income attributable to noncontrolling interests	21				—				—			21
	Other comprehensive income (loss) attributable to McKesson	$	32			$	(6	)		$	36		$	62
	Balance at March 31, 2014	$	168			$	(11	)		$	(160	)	$	(3	)
	Other comprehensive income (loss) before reclassifications	(1,845		)		(13		)		(136		)	(1,994		)
	Amounts reclassified to earnings	(10		)		3				12			5
	Other comprehensive income (loss)	$	(1,855	)		$	(10	)		$	(124	)	$	(1,989	)
Less: other comprehensive loss attributable to noncontrolling interests	(267		)		—				(12		)	(279		)
Other comprehensive income (loss) attributable to McKesson	$	(1,588	)		$	(10	)		$	(112	)	$	(1,710	)
Balance at March 31, 2015	$	(1,420	)		$	(21	)		$	(272	)	$	(1,713	)

Related_Party_Balances_and_Tra

Related Party Balances and Transactions	12 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Related Party Balances and Transactions	Related Party Balances and Transactions
	Celesio has investments in pharmacies located across Europe that are accounted for under the equity-method. Celesio maintains distribution arrangements with these pharmacies for the sale of related goods and services under which revenues of $114 million are included in our consolidated statement of operations in 2015 and receivables of $9 million are included in our consolidated balance sheet for the year ended March 31, 2015.

Segments_of_Business

Segments of Business	12 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segments of Business	Segments of Business
	We report our operations in two operating segments: McKesson Distribution Solutions and McKesson Technology Solutions. The factors for determining the reportable segments included the manner in which management evaluates the performance of the Company combined with the nature of the individual business activities. We evaluate the performance of our operating segments on a number of measures, including operating profit before interest expense, income taxes and results from discontinued operations.
	The McKesson Distribution Solutions segment distributes ethical and proprietary drugs and equipment and health and beauty care products throughout North America and internationally. This segment includes our International pharmaceutical distribution and services business which reflects the results of operations of Celesio, which we acquired in February 2014. This segment also provides specialty pharmaceutical solutions for biotech and pharmaceutical manufacturers, and practice management, technology, clinical support and business solutions to oncology and other specialty practices operating in the community setting. This segment also provides medical-surgical supply distribution, equipment, logistics and other services to healthcare providers through a network of distribution centers within the U.S. In addition, this segment sells financial, operational and clinical solutions for pharmacies (retail, hospital, alternate site) and provides consulting, outsourcing and other services. In September 2013, we sold our 49% interest in Nadro, S.A. de C.V. (“Nadro”), a pharmaceutical distributor in Mexico. Prior to the sale, financial results for Nadro were included in this segment.
	The McKesson Technology Solutions segment delivers enterprise-wide clinical, patient care, financial, supply chain, strategic management software solutions, as well as connectivity, outsourcing and other services, including remote hosting and managed services, to healthcare organizations. This segment’s customers include hospitals, physicians, homecare providers, retail pharmacies and payers primarily from North America.
	Corporate includes expenses associated with Corporate functions and projects and the results of certain equity investments. Corporate expenses are allocated to the operating segments to the extent that these items can be directly attributable to the segment.
	Financial information relating to our reportable operating segments and reconciliations to the consolidated totals is as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Revenues
	Distribution Solutions (1)
	North America pharmaceutical distribution and services	$	143,711		$	123,929		$	115,443
	International pharmaceutical distribution and services	26,358			4,485			—
	Medical-Surgical distribution & services	5,907			5,648			3,603
	Total Distribution Solutions	175,976			134,062			119,046
	Technology Solutions - products and services	3,069			3,330			3,150
	Total Revenues	$	179,045		$	137,392		$	122,196
	Operating profit
	Distribution Solutions	$	3,047		$	2,472		$	2,195
	Technology Solutions	438			448			330
	Total	3,485			2,920			2,525
	Corporate Expenses, Net	(454		)	(449		)	(335		)
	Interest Expense	(374		)	(300		)	(240		)
	Income From Continuing Operations Before Income Taxes	$	2,657		$	2,171		$	1,950
	Depreciation and amortization (2)
	Distribution Solutions	$	750		$	446		$	267
	Technology Solutions	156			169			194
	Corporate	111			120			120
	Total	$	1,017		$	735		$	581
	Expenditures for long-lived assets (3)
	Distribution Solutions	$	301		$	179		$	163
	Technology Solutions	27			47			37
	Corporate	48			52			41
	Total	$	376		$	278		$	241
	Revenues, net by geographic area (4)
	United States	$	142,810		$	122,426		$	112,102
	Foreign	36,235			14,966			10,094
	Total	$	179,045		$	137,392		$	122,196
	-1	Revenues derived from services represent less than 2% of this segment’s total revenues.
	-2	Amounts primarily include amortization of acquired intangible assets purchased in connection with acquisitions, capitalized software held for sale and capitalized software for internal use.
	-3	Long-lived assets consist of property, plant and equipment.
	-4	Net revenues were attributed to geographic areas based on the customers’ shipment locations.
	Segment assets and property, plant and equipment, net by geographic areas were as follows:
		March 31,
	(In millions)	2015			2014
	Segment assets
	Distribution Solutions	$	43,982		$	42,496
	Technology Solutions	3,281			3,573
	Total	47,263			46,069
	Corporate
	Cash and cash equivalents	5,341			4,193
	Other	1,266			1,497
	Total	$	53,870		$	51,759
	Property, plant and equipment, net
	United States	$	1,273		$	1,246
	Foreign	772			950
	Total	$	2,045		$	2,196

Quarterly_Financial_Informatio

Quarterly Financial Information (Unaudited)	12 Months Ended
	Mar. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited)
	The quarterly results of operations are not necessarily indicative of the results that may be expected for the entire year. Selected quarterly financial information for the last two years is as follows:
	(In millions, except per share amounts)	First			Second			Third			Fourth
		Quarter			Quarter			Quarter			Quarter
	Fiscal 2015
	Revenues	$	43,476		$	44,160		$	46,484		$	44,925
	Gross profit (1)	2,732			2,864			2,898			2,917
	Income after income taxes
	Continuing operations (1) (2)	$	419		$	491		$	521		$	411
	Discontinued operations (3)	(8		)	(14		)	(10		)	(267		)
	Net income	411			477			511			144
	Net income attributable to noncontrolling interests (4)	(8		)	(8		)	(39		)	(12		)
	Net income attributable to McKesson	$	403		$	469		$	472		$	132
	Earnings (loss) per common share attributable
	to McKesson (5)
	Diluted
	Continuing operations	$	1.76		$	2.05		$	2.04		$	1.69
	Discontinued operations	(0.04		)	(0.06		)	(0.04		)	(1.13		)
	Total	$	1.72		$	1.99		$	2		$	0.56
	Basic
	Continuing operations	$	1.79		$	2.08		$	2.07		$	1.72
	Discontinued operations	(0.04		)	(0.06		)	(0.04		)	(1.15		)
	Total	$	1.75		$	2.02		$	2.03		$	0.57
	-1	Financial results for the first, second, third and fourth quarters of 2015 include pre-tax charges in our Distribution Solutions segment related to our last-in-first-out (“LIFO”) method of accounting for inventories of $98 million, $94 million, $95 million and $50 million, which were recorded in cost of sales.
	-2	Fourth quarter of 2015 includes a non-cash after-tax charge of $150 million related to the settlement of controlled substance distribution claims.
	-3	Fourth quarter of 2015 includes $235 million non-cash after-tax impairment charges related to our Brazilian pharmaceutical distribution business.
	-4	Primarily reflects the guaranteed dividends of $50 million for the first nine months of 2015 and the recurring compensation of $12 million for the fourth quarter of 2015. McKesson is obligated to pay these amounts to the noncontrolling shareholders of Celesio under the Domination Agreement which became effective in December 2014.
	-5	Certain computations may reflect rounding adjustments.
	(In millions, except per share amounts)	First			Second			Third			Fourth
		Quarter			Quarter			Quarter			Quarter
	Fiscal 2014
	Revenues	$	32,239		$	32,985		$	34,336		$	37,832
	Gross profit (1)	1,930			2,021			1,850			2,551
	Income after income taxes
	Continuing operations (1) (2)	$	428		$	423		$	164		$	399
	Discontinued operations (3)	(4		)	(19		)	(99		)	(34		)
	Net income	424			404			65			365
	Net loss attributable to noncontrolling interests (4)	—			—			—			5
	Net income attributable to McKesson	$	424		$	404		$	65		$	370
	Earnings per common share attributable
	to McKesson (5)
	Diluted
	Continued operations	$	1.84		$	1.82		$	0.7		$	1.72
	Discontinued operations	(0.01		)	(0.08		)	(0.42		)	(0.14		)
	Total	$	1.83		$	1.74		$	0.28		$	1.58
	Basic
	Continuing operations	$	1.88		$	1.85		$	0.71		1.76
	Discontinued operations	(0.02		)	(0.09		)	(0.43		)	(0.15		)
	Total	$	1.86		$	1.76		$	0.28		$	1.61
	-1	Financial results for the second, third and fourth quarters of 2014 include pre-tax charges in our Distribution Solutions segment related to our LIFO method of accounting for inventories of $44 million, $142 million and $125 million, which were recorded in cost of sales. The fourth quarter of 2014 also includes a $40 million pre-tax charge to cost of sales within our Distribution Solutions segment representing the reversal of a step-up to fair value of Celesio’s inventory at the date of acquisition. Our after-tax portion of this charge from continuing operations (after allocation to noncontrolling interests) was $21 million.
	-2	Financial results for the third quarter of 2014 include an income tax charge of $122 million relating to our litigation with the Canadian Revenue Agency.
	-3	Financial results for the third quarter of 2014 include an $80 million after-tax impairment charge related to our International Technology Business, which was sold in part during the second quarter of 2015.
	-4	Primarily represents the noncontrolling shareholders’ portion of net loss from Celesio.
	-5	Certain computations may reflect rounding adjustments.

Supplementary_Consolidated_Fin

Supplementary Consolidated Financial Statement Schedule Valuation And Qualifying Accounts (Notes)	12 Months Ended
	Mar. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Supplementary Consolidated Financial Statement Schedule Valuation and Qualifying Accounts	SUPPLEMENTARY CONSOLIDATED FINANCIAL STATEMENT SCHEDULE
	VALUATION AND QUALIFYING ACCOUNTS
	For the Years Ended March 31, 2015, 2014 and 2013
	(In millions)
						Additions
	Description	Balance at Beginning of Year				Charged to Costs and Expenses				Charged to Other Accounts (3)				Deductions From Allowance Accounts (1)			Balance at End of
																	Year (2)
	Year Ended March 31, 2015
	Allowances for doubtful	$	112			$	67			$	—			$	(38	)	$	141
	accounts
	Other allowances	22				8				—				3			33
		$	134			$	75			$	—			$	(35	)	$	174
	Year Ended March 31, 2014
	Allowances for doubtful	$	121			$	36			$	(11	)		$	(34	)	$	112
	accounts
	Other allowances	15				—				10				(3		)	22
		$	136			$	36			$	(1	)		$	(37	)	$	134
	Year Ended March 31, 2013
	Allowances for doubtful	$	111			$	28			$	16			$	(34	)	$	121
	accounts
	Other allowances	14				4				1				(4		)	15
		$	125			$	32			$	17			$	(38	)	$	136
				2015				2014				2013
	-1	Deductions:
		Written off		$	(34	)		$	(39	)		$	(38	)
		Credited to other accounts		(1		)		2				—
		Total		$	(35	)		$	(37	)		$	(38	)
	-2	Amounts shown as deductions from current and non-current receivables		$	174			$	134			$	136
	-3	Primarily represents reclassifications from other balance sheet accounts.

Significant_Accounting_Policie1

Significant Accounting Policies (Policy)	12 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations: McKesson Corporation (“McKesson,” the “Company,” the “Registrant” or “we” and other similar pronouns) delivers pharmaceuticals, medical supplies and healthcare information technology that make healthcare safer while reducing costs. We conduct our business through two operating segments, McKesson Distribution Solutions and McKesson Technology Solutions, as further described in Financial Note 26, “Segments of Business.”
Basis of Presentation	Basis of Presentation: The consolidated financial statements and accompanying notes are prepared in accordance with U. S. generally accepted accounting principles (“GAAP”). The consolidated financial statements of McKesson include the financial statements of all wholly-owned subsidiaries and majority-owned or controlled companies. We also evaluate our ownership, contractual and other interests in entities to determine if they are variable interest entities (“VIEs”), if we have a variable interest in those entities and the nature and extent of those interests. Refer to Financial Note 16, “Variable Interest Entities” for more information on VIEs. Investments in business entities in which we do not have control, but have the ability to exercise significant influence over operating and financial policies, are accounted for using the equity method and our proportionate share of income or loss is recorded in other income, net. Equity investments in non-publicly traded entities are primarily accounted for using the cost method. Intercompany transactions and balances have been eliminated.
Fiscal Period	Fiscal Period: The Company’s fiscal year begins on April 1 and ends on March 31. Unless otherwise noted, all references to a particular year shall mean the Company’s fiscal year.
Reclassifications	Reclassifications: Certain prior year amounts have been reclassified to conform to the current year presentation.
Use of Estimates	Use of Estimates: The preparation of financial statements in conformity with U.S. GAAP requires that we make estimates and assumptions that affect the reported amounts in the consolidated financial statements and accompanying notes. Actual amounts could differ from those estimated amounts.
Cash and Cash Equivalents	Cash and Cash Equivalents: All highly liquid debt instruments purchased with original maturity of three months or less at the date of acquisition are included in cash and cash equivalents.
	Cash equivalents, which are available-for-sale, are carried at fair value. Cash equivalents are primarily invested in AAA rated prime and U.S. government money market funds denominated in U.S. dollars, AAA rated prime money market funds denominated in Euros, overnight repurchase agreements collateralized by U.S. government securities, Canadian government securities and/or securities that are guaranteed or sponsored by the U.S. government and an AAA rated prime money market fund denominated in British pound sterling.
	The remaining cash and cash equivalents are deposited with several financial institutions. Deposits at U.S. banks exceed the amount insured by the Federal Deposit Insurance Corporation. We mitigate the risk of our short-term investment portfolio by depositing funds with reputable financial institutions and monitoring risk profiles and investment strategies of money market funds.
Restricted Cash	Restricted Cash: Cash that is subject to legal restrictions or is unavailable for general operating purposes is classified as restricted cash and is included within prepaid expenses and other for current balances and other assets for non-current balances in the consolidated balance sheets. At March 31, 2015 and 2014, restricted cash was not material.
Marketable Securities Available for Sale	Marketable Securities Available-for-Sale: We carry our marketable securities, which are available-for-sale, at fair value and they are included in prepaid expenses and other in the consolidated balance sheets. The unrealized gains and losses, net of the related tax effect, computed in marking these securities to market have been reported within stockholders’ equity. At March 31, 2015 and 2014, marketable securities were not material.
	In determining whether an other-than-temporary decline in market value has occurred, we consider the duration that, and extent to which, the fair value of the investment is below its cost, the financial condition and future prospects of the issuer or underlying collateral of a security, and our intent and ability to retain the security in order to allow for an anticipated recovery in fair value. Other-than-temporary declines in fair value from amortized cost for available-for-sale equity securities that we intend to sell or would more likely than not be required to sell before the expected recovery of the amortized cost basis are charged to other income, net, in the period in which the loss occurs.
Concentrations of Credit Risk and Receivables	Concentrations of Credit Risk and Receivables: Our trade receivables are subject to a concentration of credit risk with customers primarily in our Distribution Solutions segment. During 2015, sales to our ten largest customers accounted for approximately 44% of our total consolidated revenues. Sales to our largest customer, CVS Caremark Corporation (“CVS”), accounted for approximately 15% of our total consolidated revenues. At March 31, 2015, trade accounts receivable from our ten largest customers were approximately 36% of total trade accounts receivable. Accounts receivable from CVS were approximately 14% of total trade accounts receivable. As a result, our sales and credit concentration is significant. We also have agreements with group purchasing organizations (“GPOs”), each of which functions as a purchasing agent on behalf of member hospitals, pharmacies and other healthcare providers. The accounts receivables balances are with individual members of the GPOs. A default in payment, a material reduction in purchases from these or any other large customers, or the loss of a large customer or customer groups could have a material adverse impact on our financial condition, results of operations and liquidity. In addition, trade receivables are subject to a concentration of credit risk with customers in the institutional, retail and healthcare provider sectors, which can be affected by a downturn in the economy and changes in reimbursement policies. This credit risk is mitigated by the size and diversity of the customer base as well as its geographic dispersion. We estimate the receivables for which we do not expect full collection based on historical collection rates and ongoing evaluations of the creditworthiness of our customers. An allowance is recorded in our consolidated financial statements for these amounts.
Financing Receivables	Financing Receivables: We assess and monitor credit risk associated with financing receivables, namely lease and notes receivables, through regular review of our collection experience in determining our allowance for loan losses. On an ongoing basis, we also evaluate credit quality of our financing receivables utilizing aging of receivables and write-offs, as well as considering existing economic conditions, to determine if an allowance is necessary. Financing receivables are derecognized if legal title to them has been transferred and all related risks and rewards incidental to ownership have passed to the buyer.  As of March 31, 2015 and 2014, financing receivables and the related allowance were not material to our consolidated financial statements.
Inventories	Inventories: We report inventories at the lower of cost or market (“LCM”). Inventories for our Distribution Solutions segment consist of merchandise held for resale. For our Distribution Solutions segment, the majority of the cost of domestic inventories is determined using the last-in, first-out (“LIFO”) method. The majority of the cost of inventories held in foreign locations is based on weighted average purchase prices using the first-in, first-out method. Technology Solutions segment inventories consist of computer hardware with cost generally determined by the standard cost method, which approximates average cost. Rebates, cash discounts, and other incentives received from vendors are accounted for as a reduction in the cost of inventory and are recognized when the inventory is sold.
	The LIFO method was used to value approximately 73% and 67% of our inventories at March 31, 2015 and 2014. If we had used the FIFO method of inventory valuation, which approximates current replacement costs, inventories would have been approximately $768 million and $431 million higher than the amounts reported at March 31, 2015 and 2014, respectively. These amounts are equivalent to our LIFO reserves. Our LIFO valuation amount includes both pharmaceutical and non-pharmaceutical products. In 2015, 2014 and 2013, we recognized LIFO related expenses of $337 million, $311 million and $13 million in cost of sales within our consolidated statements of operations. A LIFO expense is recognized when the net effect of price increases on branded pharmaceuticals and non-pharmaceutical products held in inventory exceeds the impact of price declines and shifts towards generic pharmaceuticals, including the effect of branded pharmaceutical products that have lost market exclusivity. A LIFO credit is recognized when the net effect of price declines and shifts towards generic pharmaceuticals exceeds the impact of price increases on branded pharmaceuticals and non-pharmaceutical products held in inventory.
	We believe that the average inventory costing method provides a reasonable estimation of the current cost of replacing inventory (i.e., “market”).  As such, our LIFO inventory is valued at the lower of LIFO or market.  Due to cumulative net price deflation from 2005 to 2013, we had a lower-of-cost or market (“LCM”) reserve of $60 million at March 31, 2013 which reduced pharmaceutical inventories at LIFO to market.  During 2014, the LCM reserve of $60 million was released, resulting in an increase in gross profit.  As of March 31, 2014 and 2015, inventories at LIFO did not exceed market.
Shipping and Handling Costs	Shipping and Handling Costs: We include costs to warehouse, pick, pack and deliver inventory to our customers in selling, distribution and administrative expenses.
Property, Plant and Equipment	Property, Plant and Equipment: We state our property, plant and equipment at cost and depreciate them under the straight-line method at rates designed to distribute the cost of properties over estimated service lives ranging from one to thirty years.
Goodwill	Goodwill: Goodwill is tested for impairment on an annual basis in the fourth quarter or more frequently if indicators for potential impairment exist. Impairment testing is conducted at the reporting unit level, which is generally defined as a component — one level below our Distribution Solutions and Technology Solutions operating segments, for which discrete financial information is available and segment management regularly reviews the operating results of that unit.
	The first step in goodwill testing requires us to compare the estimated fair value of a reporting unit to its carrying value. This step may be performed utilizing either a qualitative or quantitative assessment. If the carrying value of the reporting unit is lower than its estimated fair value, no further evaluation is necessary. If the carrying value of the reporting unit is higher than its estimated fair value, the second step must be performed to measure the amount of impairment loss. Under the second step, the implied fair value of goodwill is calculated in a hypothetical analysis by subtracting the fair value of all assets and liabilities of the reporting unit, including any unrecognized intangible assets, from the fair value of the reporting unit calculated in the first step of the impairment test. If the carrying value of goodwill for the reporting unit exceeds the implied fair value of goodwill, an impairment charge is recorded for that excess.
	To estimate the fair value of our reporting units, we use a combination of the market approach and the income approach. Under the market approach, we estimate fair value by comparing the business to similar businesses or guideline companies whose securities are actively traded in public markets. Under the income approach, we use a discounted cash flow model in which cash flows anticipated over several periods, plus a terminal value at the end of that time horizon, are discounted to their present value using an appropriate expected rate of return. The discount rate used for cash flows reflects capital market conditions and the specific risks associated with the business. In addition, we compare the aggregate of the reporting units’ fair value to the Company’s market capitalization as a further corroboration of the fair values. The testing requires a complex series of assumptions and judgment by management in projecting future operating results, selecting guideline companies for comparisons and assessing risks. The use of alternative assumptions and estimates could affect the fair values and change the impairment determinations.
Intangible Assets	Intangible Assets: Currently all of our intangible assets are subject to amortization and are amortized based on the pattern of their economic consumption or on a straight-line basis over their estimated useful lives, ranging from one to thirty-eight years. We review intangible assets for impairment whenever events or changes in circumstances indicate that the carrying value of the assets may not be recoverable. Determination of recoverability is based on the lowest level of identifiable estimated future undiscounted cash flows resulting from use of the asset and its eventual disposition. Measurement of any impairment loss is based on the excess of the carrying value of the asset over its fair market value.
Capitalized Software Held for Sale	Capitalized Software Held for Sale: Development costs for software held for sale, which primarily pertain to our Technology Solutions segment, are capitalized once a project has reached the point of technological feasibility. Completed projects are amortized after reaching the point of general availability using the straight-line method based on an estimated useful life of approximately three years. At each balance sheet date, or earlier if an indicator of an impairment exists, we evaluate the recoverability of unamortized capitalized software costs based on estimated future undiscounted revenues net of estimated related costs over the remaining amortization period.
Capitalized Software Held for Internal Use	Capitalized Software Held for Internal Use: We capitalize costs of software held for internal use during the application development stage of a project and amortize those costs over their estimated useful lives ranging from one to ten years. As of March 31, 2015 and 2014, capitalized software held for internal use was $435 million and $508 million, net of accumulated amortization of $1,112 million and $1,004 million, and was included in other assets in the consolidated balance sheets.
Insurance Programs	Insurance Programs: Under our insurance programs, we seek to obtain coverage for catastrophic exposures as well as those risks required to be insured by law or contract. It is our policy to retain a significant portion of certain losses primarily related to workers’ compensation and comprehensive general, product and vehicle liability. Provisions for losses expected under these programs are recorded based upon our estimate of the aggregate liability for claims incurred as well as for claims incurred but not yet reported. Such estimates utilize certain actuarial assumptions followed in the insurance industry.
Revenue Recognition	Revenue Recognition:
	Distribution Solutions
	Revenues for our Distribution Solutions segment are recognized when product is delivered and title passes to the customer or when services have been rendered and there are no further obligations to the customer.
	Revenues are recorded net of sales returns, allowances, rebates and other incentives. Our sales return policy generally allows customers to return products only if they can be resold for value or returned to suppliers for full credit. Sales returns are accrued based on estimates at the time of sale to the customer. Sales returns from customers were approximately $2.7 billion in 2015 and $1.9 billion in 2014 and 2013. Taxes collected from customers and remitted to governmental authorities are presented on a net basis; that is, they are excluded from revenues.
	Revenues for our Distribution Solutions segment include large volume sales of pharmaceuticals primarily to a limited number of large customers who warehouse their own product. We order bulk product from the manufacturer, receive and process the product primarily through our central distribution facility and deliver the bulk product (generally in the same form as received from the manufacturer) directly to our customers’ warehouses. We also record revenues for direct store deliveries from most of these same customers. Direct store deliveries are shipments from the manufacturer to our customers of a limited category of products that require special handling. We assume the primary liability to the manufacturer for these products.
	Revenues are recorded gross when we are the primary party obligated in the transaction, take title to and possession of the inventory, are subject to inventory risk, have latitude in establishing prices, assume the risk of loss for collection from customers as well as delivery or return of the product, are responsible for fulfillment and other customer service requirements, or the transactions have several but not all of these indicators.
	Our Distribution Solutions segment also engages in multiple-element arrangements, which may contain a combination of various products and services. Revenue from a multiple-element arrangement is allocated to the separate elements based on their relative selling price and recognized in accordance with the revenue recognition criteria applicable to each element. Relative selling price is determined based on vendor-specific objective evidence (“VSOE”) of selling price, if available, third-party evidence (“TPE”), if VSOE of selling price is not available, or estimated selling price (“ESP”), if neither VSOE of selling price nor TPE is available.
	Technology Solutions
	Revenues for our Technology Solutions segment are generated primarily by licensing software and software systems (consisting of software, hardware and maintenance support), providing software as a service or SaaS-based solutions and providing claims processing, outsourcing and professional services. Revenue for this segment is recognized as follows:
	Software systems are marketed under information systems agreements as well as service agreements. Perpetual software arrangements are recognized at the time of delivery or under the percentage-of-completion method if the arrangements require significant production, modification or customization of the software. Contracts accounted for under the percentage-of-completion method are generally measured based on the ratio of labor hours incurred to date to total estimated labor hours to be incurred. Changes in estimates to complete and revisions in overall profit estimates on these contracts are charged to earnings in the period in which they are determined. We accrue for contract losses if and when the current estimate of total contract costs exceeds total contract revenue.
	Revenue from time-based software license agreements is recognized ratably over the term of the agreement. Software implementation fees are recognized as the work is performed or under the percentage-of-completion method. Maintenance and support agreements are marketed under annual or multi-year agreements and are recognized ratably over the period covered by the agreements. Hardware revenues are generally recognized upon delivery.
	SaaS-based subscription, content and transaction processing fees are generally marketed under annual and multi-year agreements and are recognized ratably over the contracted terms beginning on the service start date for fixed fee arrangements and recognized as transactions are performed beginning on the service start date for per-transaction fee arrangements. Remote processing service fees are recognized monthly as the service is performed. Outsourcing service revenues are recognized as the service is performed.
	We also offer certain products on an application service provider basis, making our software functionality available on a remote hosting basis from our data centers. The data centers provide system and administrative support, as well as hosting services. Revenue on products sold on an application service provider basis is recognized on a monthly basis over the term of the contract beginning on the service start date of products hosted.
	This segment engages in multiple-element arrangements, which may contain any combination of software, hardware, implementation, SaaS-based offerings, consulting services or maintenance services. For multiple-element arrangements that do not include software, revenue is allocated to the separate elements based on their relative selling price and recognized in accordance with the revenue recognition criteria applicable to each element. Relative selling price is determined based on VSOE of selling price if available, TPE, if VSOE of selling price is not available, or ESP if neither VSOE of selling price nor TPE is available. For multiple-element arrangements accounted for in accordance with specific software accounting guidance when some elements are delivered prior to others in an arrangement and VSOE of fair value exists for the undelivered elements, revenue for the delivered elements is recognized upon delivery of such items. The segment establishes VSOE for hardware and implementation and consulting services based on the price charged when sold separately, and for maintenance services, based on renewal rates offered to customers. Revenue for the software element is recognized under the residual method only when fair value has been established for all of the undelivered elements in an arrangement. If fair value cannot be established for any undelivered element, all of the arrangement’s revenue is deferred until the delivery of the last element or until the fair value of the undelivered element is determinable. For multiple-element arrangements with both software elements and nonsoftware elements, arrangement consideration is allocated between the software elements as a whole and nonsoftware elements.  The segment then further allocates consideration to the individual elements within the software group, and revenue is recognized for all elements under the applicable accounting guidance and our policies described above.
Supplier Incentives	Supplier Incentives: Fees for service and other incentives received from suppliers, relating to the purchase or distribution of inventory, are generally reported as a reduction to cost of goods sold. We consider these fees and other incentives to represent product discounts and as a result, the amounts are recorded as a reduction of product cost and are recognized through cost of goods sold upon the sale of the related inventory.
Supplier Reserves	Supplier Reserves: We establish reserves against amounts due from suppliers relating to various price and rebate incentives, including deductions or billings taken against payments otherwise due to them. These reserve estimates are established based on judgment after considering the status of current outstanding claims, historical experience with the suppliers, the specific incentive programs and any other pertinent information available. We evaluate the amounts due from suppliers on a continual basis and adjust the reserve estimates when appropriate based on changes in factual circumstances. As of March 31, 2015 and 2014 supplier reserves were $167 million and $181 million. The ultimate outcome of any outstanding claims may be different than our estimate. All of the supplier reserves at March 31, 2015 and 2014 pertain to our Distribution Solutions segment.
Income Taxes	Income Taxes: We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statements and the tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Tax benefits from uncertain tax positions are recognized when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. The amount recognized is measured as the largest amount of tax benefit that is greater than 50 percent likely of being realized upon effective settlements. Deferred taxes are not provided on undistributed earnings of our foreign operations that are considered to be permanently reinvested.
Foreign Currency Translation	Foreign Currency Translation: Our international subsidiaries generally consider their local currency to be their functional currency. Assets and liabilities of these international subsidiaries are translated into U.S. dollars at year-end exchange rates and revenues and expenses are translated at average exchange rates during the year. Currency translation adjustments for the year are included in other comprehensive income or loss in the statements of consolidated comprehensive income, and the cumulative effect is included in the stockholders’ equity section of the consolidated balance sheets. When we sell all or substantially all of an international entity, the related share of the cumulative currency translation adjustment is removed from stockholders’ equity and is included in the gain or loss on sale in the consolidated statements of operations. Realized gains and losses from currency exchange transactions are recorded in operating expenses in the consolidated statements of operations and were not material to our consolidated results of operations in 2015, 2014 or 2013.
Derivative Financial Instruments	Derivative Financial Instruments: Derivative financial instruments are used principally in the management of foreign currency and interest rate exposures and are recorded on the consolidated balance sheets at fair value. If a derivative is designated as a fair value hedge, the changes in the fair value of the derivative and of the hedged item attributable to the hedged risk are recognized as a charge or credit to earnings. If the derivative is designated as a cash flow hedge, the effective portions of changes in the fair value of the derivative are included in other comprehensive income or loss in the statements of consolidated comprehensive income, and the cumulative effect is included in the stockholders’ equity section of the consolidated balance sheets. The cumulative changes in fair value are reclassed to the consolidated statements of operations when the hedged item affects earnings. We periodically evaluate hedge effectiveness, and ineffective portions of changes in the fair value of cash flow hedges are recognized as a charge or credit to earnings. Derivative instruments not designated as hedges are marked-to-market at the end of each accounting period with the change included in earnings.
Comprehensive Income	Comprehensive Income: Comprehensive income consists of two components, net income and other comprehensive income. Other comprehensive income refers to revenue, expenses, and gains and losses that under GAAP are recorded as an element of shareholders’ equity but are excluded from net income. Our other comprehensive income consists of foreign currency translation adjustments from those subsidiaries where the local currency is the functional currency, unrealized gains and losses on cash flow hedges, as well as unrealized gains and losses on retirement-related benefit plans.
Noncontrolling Interests and Redeemable Noncontrolling Interests	Noncontrolling and Redeemable Noncontrolling Interests: Noncontrolling interests represent the portion of profit or loss, net assets and comprehensive income that is not allocable to McKesson Corporation. In 2015, net income attributable to noncontrolling interests primarily represents guaranteed dividends and recurring compensation that McKesson is obligated to pay to the noncontrolling shareholders of Celesio. Noncontrolling interests with redemption features, such as put rights, that are not solely within the Company’s control are considered redeemable noncontrolling interests.  Redeemable noncontrolling interests are presented outside of Stockholders’ Equity on our consolidated balance sheet. Refer to Financial Note 3, “Noncontrolling Interests,” for more information.
Share-Based Compensation	Share-Based Compensation: We account for all share-based compensation transactions using a fair-value based measurement method. The share-based compensation expense, for the portion of the awards that is ultimately expected to vest, is recognized on a straight-line basis over the requisite service period. The compensation expense recognized has been classified in the consolidated statements of operations or capitalized on the consolidated balance sheets in the same manner as cash compensation paid to our employees.
Loss Contingencies	Loss Contingencies: We are subject to various claims, other pending and potential legal actions for damages, investigations relating to governmental laws and regulations and other matters arising out of the normal conduct of our business. When a loss is considered probable and reasonably estimable, we record a liability in the amount of our best estimate for the ultimate loss. However, the likelihood of a loss with respect to a particular contingency is often difficult to predict and determining a meaningful estimate of the loss or a range of loss may not be practicable based on the information available and the potential effect of future events and decisions by third parties that will determine the ultimate resolution of the contingency. Moreover, it is not uncommon for such matters to be resolved over many years, during which time relevant developments and new information must be reevaluated at least quarterly to determine both the likelihood of potential loss and whether it is possible to reasonably estimate a range of possible loss. When a loss is probable but a reasonable estimate cannot be made, disclosure of the proceeding is provided.
	Disclosure also is provided when it is reasonably possible that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the recorded provision. We review all contingencies at least quarterly to determine whether the likelihood of loss has changed and to assess whether a reasonable estimate of the loss or range of the loss can be made. As discussed above, development of a meaningful estimate of loss or a range of potential loss is complex when the outcome is directly dependent on negotiations with or decisions by third parties, such as regulatory agencies, the court system and other interested parties. Such factors bear directly on whether it is possible to reasonably estimate a range of potential loss and boundaries of high and low estimate.
Business Combinations	Business Combinations: We account for acquired businesses using the acquisition method of accounting, which requires that once control is obtained of a business, 100% of the assets acquired and liabilities assumed, including amounts attributed to noncontrolling interests, be recorded at the date of acquisition at their respective fair values. Any excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill. Acquisition-related expenses and related restructuring costs are expensed as incurred.
	Several valuation methods may be used to determine the fair value of assets acquired and liabilities assumed.  For intangible assets, we typically use the income method.  This method starts with a forecast of all of the expected future net cash flows for each asset.  These cash flows are then adjusted to present value by applying an appropriate discount rate that reflects the risk factors associated with the cash flow streams.  Some of the more significant estimates and assumptions inherent in the income method or other methods include the amount and timing of projected future cash flows, the discount rate selected to measure the risks inherent in the future cash flows and the assessment of the asset’s life cycle and the competitive trends impacting the asset, including consideration of any technical, legal, regulatory, or economic barriers to entry.  Determining the useful life of an intangible asset also requires judgment as different types of intangible assets will have different useful lives and certain assets may even be considered to have indefinite useful lives.
Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements
	Business Combinations: In November 2014, amended guidance related to pushdown accounting was issued and became effective immediately. This guidance provides an acquired entity with an option to use the acquirer’s accounting and reporting basis in the preparation of its separate financial statements when an acquirer obtains control of the acquired entity. The option to apply pushdown accounting can be elected for each individual change-of-control event.  The adoption of this amended guidance did not have a material effect on our consolidated financial statements.
	Cumulative Translation Adjustment: In the first quarter of 2015, we adopted amended guidance for parent’s accounting for the cumulative translation adjustment upon derecognition of certain subsidiaries or group of assets within a foreign entity or of an investment in a foreign entity.  The amended guidance requires the release of any cumulative translation adjustment into net income only upon complete or substantially complete liquidation of a controlling interest in a subsidiary or a group of assets within a foreign entity.  Also, it requires the release of all or a pro rata portion of the cumulative translation adjustment to net income in the case of sale of an equity method investment that is a foreign entity.  The adoption of this amended guidance did not have a material effect on our consolidated financial statements.
	Recently Issued Accounting Pronouncements Not Yet Adopted
	Fees Paid in a Cloud Computing Arrangement:  In April 2015, amended guidance was issued for a customer’s accounting for fees paid in a cloud computing arrangement.  The amended guidance requires customers to determine whether or not an arrangement contains a software license element. If the arrangement contains a software element, the related fees paid should be accounted for as an acquisition of a software license. If the arrangement does not contain a software license, it is accounted for as a service contract. The amended guidance will become effective for us commencing in the first quarter of 2017.  Early adoption is permitted.  We are currently evaluating the impact of this amended guidance on our consolidated financial statements.
	Debt Issuance Costs:  In April 2015, amended guidance was issued for the balance sheet presentation of debt issuance costs and will become effective for us commencing in the first quarter of 2017.  Early adoption is permitted.  The amended guidance requires debt issuance costs related to a recognized debt liability be reported in the balance sheet as a direct deduction from the carrying amount of that debt liability.  The recognition and measurement guidance for debt issuance costs are not affected by the amended guidance. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements.
	Consolidation: In February 2015, amended guidance was issued for consolidating legal entities in which a reporting entity holds a variable interest.  The amended guidance modifies the evaluation of whether limited partnerships and similar legal entities are VIEs and changes the consolidation analysis of reporting entities that are involved with VIEs that have fee arrangements and related party relationships. The amended guidance will become effective for us commencing in the first quarter of 2017.  Early adoption is permitted.  We are currently evaluating the impact of this amended guidance on our consolidated financial statements.
	Discontinued Operations: In April 2014, amended guidance was issued for reporting of discontinued operations and disclosures of disposals of components.  The amended guidance revises the criteria for disposals to qualify as discontinued operations and permits significant continuing involvement and continuing cash flows with the discontinued operation.  In addition, the amended guidance requires additional disclosures for discontinued operations and new disclosures for individually material disposal transactions that do not meet the definition of a discontinued operation.  The amended guidance is effective for us prospectively commencing in the first quarter of 2016.  Early adoption is permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements.
	Revenue Recognition: In May 2014, amended guidance was issued for recognizing revenue from contracts with customers.  The amended guidance eliminated industry specific guidance and applies to all companies.  Revenues will be recognized when an entity satisfies a performance obligation by transferring control of a promised good or service to a customer in an amount that reflects the consideration to which the entity expects to be entitled for that good or service. Revenue from a contract that contains multiple performance obligations is allocated to each performance obligation generally on a relative standalone selling price basis. The amended guidance also requires additional quantitative and qualitative disclosures. The amended guidance is effective for us commencing in the first quarter of 2018.  The amended guidance allows for either full retrospective adoption or modified retrospective adoption. Early adoption is not permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements.

Business_Combinations_Tables

Business Combinations (Tables) (Celesio [Member])	12 Months Ended
	Mar. 31, 2015
Celesio [Member]
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]
	(In millions)	Amounts			Measurement Period Adjustments			Amounts Recognized as of Acquisition Date (Final as Adjusted)
		Previously Recognized as of
		Acquisition Date
		(Provisional)
	Receivables	$	3,425		$	(49	)	$	3,376
	Other current assets, net of cash and cash equivalents acquired	2,413			17			2,430
	Goodwill	3,570			655			4,225
	Intangible assets	3,018			(709		)	2,309
	Other long-term assets	1,272			(39		)	1,233
	Current liabilities	(4,096		)	(28		)	(4,124		)
	Short-term borrowings and current portion of long-term debt	(1,990		)	—			(1,990		)
	Long-term debt	(322		)	—			(322		)
	Other long-term liabilities	(1,293		)	158			(1,135		)
	Fair value of net assets, less cash and cash equivalents	5,997			5			6,002
	Less: Noncontrolling Interests	(1,500		)	(5		)	(1,505		)
	Net assets acquired, net of cash and cash equivalents	$	4,497		$	—		$	4,497

Noncontrolling_Interests_Sched

Noncontrolling Interests Schedule of Changes in Noncontrolling Interests (Tables)	12 Months Ended
	Mar. 31, 2015
Noncontrolling Interest [Abstract]
Schedule of Changes In Noncontrolling Interests [Table Text Block]	Changes in noncontrolling interests and redeemable noncontrolling interests were as follows:
	(In millions)	Noncontrolling			Redeemable
		Interests			Noncontrolling
					Interests
	Balance, March 31, 2014	$	1,796		$	—
	Net income attributable to noncontrolling interests (1)	5			62
	Other comprehensive loss	(174		)	(105		)
	Purchase of noncontrolling interests	(60		)	(9		)
	Reclassification from Total Equity to Redeemable Noncontrolling Interests (2)	(1,500		)	1,500
	Reclassification of guaranteed dividends and recurring compensation to other accrued liabilities	—			(62		)
	Other	17			—
	Balance, March 31, 2015	$	84		$	1,386
	-1	Includes the Guaranteed Dividend of $50 million for Celesio’s fiscal year ended December 31, 2014 and the Compensation Amount of $12 million for the fourth quarter of 2015
	-2	Includes net foreign currency losses of $138 million attributable to noncontrolling interests

Discontinued_Operations_Discon

Discontinued Operations Discontinued Operations (Tables)	12 Months Ended
	Mar. 31, 2015
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Results for Discontinued Operations	A summary of results of discontinued operations is as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Revenues	$	2,196		$	637		$	259
	Loss from discontinued operations	$	(321	)	$	(177	)	$	(32	)
	Loss on sale	(6		)	(5		)	—
	Loss from discontinued operations before income tax	(327		)	(182		)	(32		)
	Income tax benefit	28			26			7
	Loss from discontinued operations, net of tax	$	(299	)	$	(156	)	$	(25	)

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	12 Months Ended
	Mar. 31, 2015
Share-based Compensation [Abstract]
Components Of Share-Based Compensation Expense And Related Tax Benefits	The components of share-based compensation expense and related tax benefits are as follows:
		Years Ended March 31,
	(In millions)	2015				2014				2013
	Restricted stock unit awards (1)	$	137			$	126			$	132
	Stock options	24				22				24
	Employee stock purchase plan	13				12				11
	Share-based compensation expense	174				160				167
	Tax benefit for share-based compensation expense (2)	(61		)		(55		)		(59		)
	Share-based compensation expense, net of tax	$	113			$	105			$	108
Schedule Of Weighted-Average Assumptions Used To Estimate The Fair Value Of Employee Stock Options	Weighted-average assumptions used to estimate the fair value of employee stock options were as follows:
		Years Ended March 31,
		2015		2014		2013
	Expected stock price volatility	22%		22%		27%
	Expected dividend yield	0.60%		0.70%		0.90%
	Risk-free interest rate	1.30%		0.70%		0.80%
	Expected life (in years)	4		4		5
Summary Of Options Outstanding	The following is a summary of stock options outstanding at March 31, 2015:
									Options Outstanding						Options Exercisable
	Range of Exercise								Number of		Weighted-		Weighted-		Number of	Weighted-
	Prices								Options		Average		Average		Options	Average
									Outstanding		Remaining		Exercise Price		Exercisable at	Exercise Price
									at Year End		Contractual				Year End
									(In millions)		Life (Years)				(In millions)
	$	40.46		–	$	133.27			4		3		$	79.38	2	$	68.8
	133.28			–	226.05				1		6		182.38		—	155.87
									5						2
Stock Option Activity	The following table summarizes stock option activity during 2015:
	(In millions, except per share data)	Shares		Weighted-				Weighted-		Aggregate
				Average				Average		Intrinsic
				Exercise				Remaining		Value (2)
				Price				Contractual
								Term (Years)
	Outstanding, March 31, 2014	6		$	78.07			4		$	473
	Granted	1		184.84
	Exercised	-2		67.64
	Outstanding, March 31, 2015	5		$	95.01			4		$	539
	Vested and expected to vest (1)	5		$	95.01			4		$	538
	Vested and exercisable, March 31, 2015	2		69.27				3		363
Data Related To Stock Option Activity	The following table provides data related to stock option activity:
		Years Ended March 31,
	(In millions, except per share data)	2015				2014				2013
	Weighted-average grant date fair value per stock option	$	35.49			$	21.45			$	19.63
	Aggregate intrinsic value on exercise	$	153			$	144			$	107
	Cash received upon exercise	$	76			$	111			$	106
	Tax benefits realized related to exercise	$	60			$	55			$	41
	Total fair value of stock options vested	$	20			$	24			$	24
	Total compensation cost, net of estimated forfeitures, related to unvested stock options not yet recognized, pre-tax	$	22			$	29			$	37
	Weighted-average period in years over which stock option compensation cost is expected to be recognized	2				1				1
RSU Activity	The following table summarizes restricted stock unit award activity during 2015:
	(In millions, except per share data)	Shares		Weighted-
				Average
				Grant Date Fair
				Value Per Share
	Nonvested, March 31, 2014	4		$	93.25
	Granted	1		187.03
	Vested	-1		84.28
	Nonvested, March 31, 2015	4		$	129.57
Data Related to RSU Activity	The following table provides data related to restricted stock unit award activity:
		Years Ended March 31,
	(In millions)	2015				2014				2013
	Total fair value of shares vested	$	126			$	184			$	66
	Total compensation cost, net of estimated forfeitures, related to nonvested restricted stock unit awards not yet recognized, pre-tax	$	206			$	236			$	210
	Weighted-average period in years over which restricted stock unit award cost is expected to be recognized	2				2				2

Other_Income_Expense_Net_Table

Other Income (Expense), Net (Tables)	12 Months Ended
	Mar. 31, 2015
Other Nonoperating Income (Expense) [Abstract]
Other Income (Expense), Net
		Years Ended March 31,
	(In millions)	2015		2014		2013
	Interest income	$	20	$	16	$	22
	Equity in earnings (loss), net (1)	12		—		3
	Other, net (1)	31		16		9
	Total	$	63	$	32	$	34
	-1	Primarily recorded within our Distribution Solutions segment.

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income from Continuing Operations before Income Taxes
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Income from continuing operations before income taxes
	U.S.	$	1,893		$	1,554		$	1,562
	Foreign	764			617			388
	Total income from continuing operations before income taxes	$	2,657		$	2,171		$	1,950
Components of Provision For Income Taxes Related to Continuing Operations	Income tax expense related to continuing operations consists of the following:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Current
	Federal	$	453		$	484		$	(84	)
	State	90			64			14
	Foreign	101			193			46
	Total current	644			741			(24		)
	Deferred
	Federal	195			24			538
	State	53			10			80
	Foreign	(77		)	(18		)	(7		)
	Total deferred	171			16			611
	Income tax expense	$	815		$	757		$	587
Reconciliation Between Effective Tax Rate on Income From Continuing Operations and Statutory Tax Rate	The reconciliation between our effective tax rate on income from continuing operations and statutory tax rate is as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Income tax expense at federal statutory rate	$	930		$	760		$	683
	State income taxes net of federal tax benefit	81			57			58
	Foreign income taxed at various rates	(247		)	(177		)	(143		)
	Canadian litigation	—			122			—
	Controlled substance distribution reserve	58			—			—
	Unrecognized tax benefits and settlements	10			(6		)	1
	Tax credits	(10		)	(6		)	(13		)
	Other, net	(7		)	7			1
	Income tax expense	$	815		$	757		$	587
Components of Deferred Tax Assets and Liabilities	Deferred tax balances consisted of the following:
		March 31,
	(In millions)	2015			2014
	Assets
	Receivable allowances	$	83		$	94
	Deferred revenue	72			136
	Compensation and benefit related accruals	681			632
	Net operating loss and credit carryforwards	316			337
	Other	266			287
	Subtotal	1,418			1,486
	Less: valuation allowance	(229		)	(200		)
	Total assets	1,189			1,286
	Liabilities
	Inventory valuation and other assets	(2,333		)	(2,161		)
	Fixed assets and systems development costs	(324		)	(320		)
	Intangibles	(1,073		)	(1,477		)
	Other	(61		)	(117		)
	Total liabilities	(3,791		)	(4,075		)
	Net deferred tax liability	$	(2,602	)	$	(2,789	)
	Current net deferred tax asset	$	26		$	42
	Current net deferred tax liability	(1,819		)	(1,588		)
	Long-term deferred tax asset	50			19
	Long-term deferred tax liability	(859		)	(1,262		)
	Net deferred tax liability	$	(2,602	)	$	(2,789	)
Gross Unrecognized Tax Benefits	The following table summarizes the activity related to our gross unrecognized tax benefits for the last three years:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Unrecognized tax benefits at beginning of period	$	647		$	560		$	595
	Additions based on tax positions related to prior years	62			106			46
	Reductions based on tax positions related to prior years	(18		)	(23		)	(106		)
	Additions based on tax positions related to current year	27			23			31
	Reductions based on settlements	(65		)	(4		)	(2		)
	Reductions based on the lapse of the applicable statutes of limitations	(12		)	(7		)	(2		)
	Exchange rate fluctuations	(25		)	(8		)	(2		)
	Unrecognized tax benefits at end of period	$	616		$	647		$	560

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Basic and Diluted Earnings per Common Share	The computations for basic and diluted earnings per common share are as follows:
		Years Ended March 31,
	(In millions, except per share amounts)	2015			2014			2013
	Income from continuing operations	$	1,842		$	1,414		$	1,363
	Net loss (income) attributable to noncontrolling interests	(67		)	5			—
	Income from continuing operations attributable to McKesson	1,775			1,419			1,363
	Loss from discontinued operations, net of tax	(299		)	(156		)	(25		)
	Net income attributable to McKesson	$	1,476		$	1,263		$	1,338
	Weighted average common shares outstanding:
	Basic	232			229			235
	Effect of dilutive securities:
	Options to purchase common stock	1			1			1
	Restricted stock units	2			3			3
	Diluted	235			233			239
	Earnings (loss) per common share attributable to McKesson: (1)
	Diluted
	Continuing operations	$	7.54		$	6.08		$	5.69
	Discontinued operations	(1.27		)	(0.67		)	(0.10		)
	Total	$	6.27		$	5.41		$	5.59
	Basic
	Continuing operations	$	7.66		$	6.19		$	5.81
	Discontinued operations	(1.29		)	(0.68		)	(0.10		)
	Total	$	6.37		$	5.51		$	5.71

Receivables_Net_Tables

Receivables, Net (Tables)	12 Months Ended
	Mar. 31, 2015
Receivables, Net, Current [Abstract]
Schedule of Accounts Receivable
		March 31,
	(In millions)	2015			2014
	Customer accounts	$	13,117		$	12,169
	Other	2,965			1,740
	Total	16,082			13,909
	Allowances	(168		)	(129		)
	Net	$	15,914		$	13,780

Property_Plant_and_Equipment_N1

Property, Plant and Equipment, Net (Tables)	12 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment, Net [Abstract]
Schedule of Property, Plant and Equipment, Net
		March 31,
	(In millions)	2015			2014
	Land	$	207		$	221
	Building, machinery, equipment and other	3,237			3,155
	Total property, plant and equipment	3,444			3,376
	Accumulated depreciation	(1,399		)	(1,180		)
	Property, plant and equipment, net	$	2,045		$	2,196

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets, Net (Tables)	12 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the Carrying Amount of Goodwill	Changes in the carrying amount of goodwill were as follows:
	(In millions)	Distribution				Technology				Total
		Solutions				Solutions
	Balance, March 31, 2013	$	4,413			$	1,992			$	6,405
	Goodwill acquired	3,649				—				3,649
	Amount reclassified to assets held-for-sale	(1		)		(127		)		(128		)
	Acquisition accounting, transfers and other adjustments	13				(12		)		1
	Foreign currency translation adjustments, net	4				(4		)		—
	Balance, March 31, 2014	$	8,078			$	1,849			$	9,927
	Goodwill acquired	93				—				93
	Amount reclassified to assets held-for-sale	(14		)		(1		)		(15		)
	Acquisition accounting, transfers and other adjustments	625				—				625
	Foreign currency translation adjustments, net	(788		)		(25		)		(813		)
	Balance, March 31, 2015	$	7,994			$	1,823			$	9,817
Information Regarding Intangible Assets	Information regarding intangible assets is as follows:
		March 31, 2015												March 31, 2014
	(Dollars in millions)	Weighted		Gross				Accumulated				Net		Gross		Accumulated			Net
		Average		Carrying				Amortization				Carrying		Carrying		Amortization			Carrying
		Remaining		Amount								Amount		Amount					Amount
		Amortization
		Period
		(Years)
	Customer lists	8		$	2,683			$	(1,116	)		$	1,567	$	3,235	$	(863	)	$	2,372
	Service agreements	15		957				(215		)		742		995		(173		)	822
	Pharmacy licenses	26		874				(65		)		809		1,219		(11		)	1,208
	Trademarks and trade names	15		315				(82		)		233		367		(59		)	308
	Technology	3		213				(184		)		29		219		(173		)	46
	Other	4		162				(101		)		61		166		(51		)	115
	Total			$	5,204			$	(1,763	)		$	3,441	$	6,201	$	(1,330	)	$	4,871

Capitalized_Software_Held_for_1

Capitalized Software Held for Sale (Tables)	12 Months Ended
	Mar. 31, 2015
Capitalized Computer Software, Net [Abstract]
Capitalized Software Held for Sale	Changes in the carrying amount of capitalized software held for sale, net, which is included in other assets in the consolidated balance sheets, were as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Balance, at beginning of period	$	103		$	126		$	144
	Amounts capitalized	34			40			49
	Amortization expense	(40		)	(50		)	(56		)
	Impairment charges	—			(12		)	(10		)
	Foreign currency translations adjustments, net	(6		)	(1		)	(1		)
	Balance, at end of period	$	91		$	103		$	126

Debt_and_Financing_Activities_

Debt and Financing Activities (Tables)	12 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule of Long-Term Debt	Information regarding long-term debt is as follows:
		March 31,
	(In millions)	2015			2014
	Denominated in U.S. Dollars
	Floating Rate Notes due September 10, 2015	$	400		$	400
	0.95% Notes due December 4, 2015	500			499
	3.25% Notes due March 1, 2016	600			599
	5.70% Notes due March 1, 2017	500			500
	1.29% Notes due March 10, 2017	700			700
	1.40% Notes due March 15, 2018	499			499
	7.50% Notes due February 15, 2019	349			349
	2.28% Notes due March 15, 2019	1,100			1,100
	4.75% Notes due March 1, 2021	599			598
	2.70% Notes due December 15, 2022	400			400
	2.85% Notes due March 15, 2023	400			400
	3.80% Notes due March 15, 2024	1,100			1,100
	7.65% Debentures due March 1, 2027	175			175
	6.00% Notes due March 1, 2041	493			493
	4.88% Notes due March 15, 2044	800			800
	Other	26			27
	Denominated in Euro and other foreign currencies
	4.00% Bonds due October 18, 2016	388			507
	4.50% Bonds due April 26, 2017	563			737
	Promissory Notes	—			297
	Bank liabilities and other	117			166
	Total debt	9,709			10,346
	Less current portion	(1,529		)	(1,417		)
	Total long-term debt	$	8,180		$	8,929

Pension_Benefits_Tables

Pension Benefits (Tables) (Pension Plans, Defined Benefit [Member])	12 Months Ended
	Mar. 31, 2015
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Net Periodic Expense for Pension Plans	The net periodic expense for our pension plans, which includes net pension expense of Celesio beginning February 2014, is as follows:
		U.S. Plans											Non-U.S. Plans
		Years Ended March 31,											Years Ended March 31,
	(In millions)	2015				2014				2013			2015				2014			2013
	Service cost - benefits earned during the year	$	1			$	4			$	4		$	16			$	6		$	3
	Interest cost on projected benefit obligation	19				19				21			34				11			7
	Expected return on assets	(21		)		(20		)		(20		)	(30		)		(12		)	(8		)
	Amortization of unrecognized actuarial loss, prior service costs and net transitional obligation	19				32				28			3				4			4
	Curtailment/settlement loss (gain)	—				—				—			6				(1		)	—
	Net periodic pension expense	$	18			$	35			$	33		$	29			$	8		$	6
Schedule of Changes in Benefit Obligations and Plan Assets for Pension Plans	Information regarding the changes in benefit obligations and plan assets for our pension plans is as follows:
		U.S. Plans								Non-U.S. Plans
		Years Ended March 31,								Years Ended March 31,
	(In millions)	2015				2014				2015			2014
	Change in benefit obligations
	Benefit obligation at beginning of period (1)	$	540			$	580			$	934		$	156
	Service cost	1				4				16			6
	Interest cost	19				19				34			11
	Actuarial loss (gain)	53				(24		)		194			15
	Benefit payments	(30		)		(30		)		(49		)	(12		)
	Amendments	—				(9		)		(6		)	—
	Acquisitions	—				—				—			740
	Foreign exchange impact and other	—				—				(160		)	18
	Benefit obligation at end of period (1)	$	583			$	540			$	963		$	934
	Change in plan assets
	Fair value of plan assets at beginning of period	$	300			$	290			$	590		$	135
	Actual return on plan assets	16				28				88			11
	Employer and participant contributions	12				12				73			12
	Benefits paid	(30		)		(30		)		(49		)	(10		)
	Acquisitions	—				—				—			426
	Foreign exchange impact and other	—				—				(90		)	16
	Fair value of plan assets at end of period	$	298			$	300			$	612		$	590
	Funded status at end of period	$	(285	)		$	(240	)		$	(351	)	$	(344	)
	Amounts recognized on the balance sheet
	Current liabilities	$	(17	)		$	(13	)		$	(6	)	$	(9	)
	Long-term liabilities	(268		)		(227		)		(345		)	(335		)
	Total	$	(285	)		$	(240	)		$	(351	)	$	(344	)
Schedule of Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets for Pension Plans	The following table provides the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for all our pension plans with an accumulated benefit obligation in excess of plan assets.
		U.S. Plans								Non-U.S. Plans
		March 31,								March 31,
	(In millions)	2015				2014				2015			2014
	Projected benefit obligation	$	583			$	540			$	963		$	934
	Accumulated benefit obligation	583				540				897			894
	Fair value of plan assets	298				300				612			590
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	Amounts recognized in accumulated other comprehensive income (pre-tax) consist of:
		U.S. Plans								Non-U.S. Plans
		March 31,								March 31,
	(In millions)	2015				2014				2015			2014
	Net actuarial loss	$	220			$	188			$	175		$	71
	Prior service credit	—				(7		)		(6		)	—
	Total	$	220			$	181			$	169		$	71
Schedule of Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income	Other changes in accumulated other comprehensive income (pre-tax) were as follows:
		U.S. Plans											Non-U.S. Plans
		Years Ended March 31,											Years Ended March 31,
	(In millions)	2015				2014				2013			2015				2014			2013
	Net actuarial loss (gain)	$	58			$	(31	)		$	59		$	117			$	12		$	11
	Prior service credit	—				(8		)		—			(8		)		—			—
	Amortization of:
	Net actuarial loss	(27		)		(32		)		(27		)	(5		)		(4		)	(4		)
	Prior service credit (cost)	8				—				(1		)	2				2			—
	Foreign exchange impact and other	—				(1		)		—			(8		)		4			(4		)
	Total recognized in other comprehensive loss (income)	$	39			$	(72	)		$	31		$	98			$	14		$	3
Schedule of Weighted-Average Assumptions Used to Estimate Net Periodic Pension Expense and Actuarial Present Value of Benefit Obligations	Weighted-average assumptions used to estimate the net periodic pension expense and the actuarial present value of benefit obligations were as follows:
		U.S. Plans									Non-U.S. Plans
		Years Ended March 31,									Years Ended March 31,
		2015			2014			2013			2015		2014			2013
	Net periodic pension expense
	Discount rates	3.74	%		3.39	%		4.11	%		3.85	%	3.95	%		4.5	%
	Rate of increase in compensation	4			4			4			3.11		2.66			3.1
	Expected long-term rate of return on plan assets	7.25			7.25			7.25			5.39		5.71			6.13
	Benefit obligation
	Discount rates	3.18	%		3.58	%		3.4	%		2.5	%	3.92	%		4.1	%
	Rate of increase in compensation	4			4			4			3.24		3.27			3.05
Schedule of Sensitivity to Changes in Weighted-Average Discount Rate for U.S. Pension Plans	Sensitivity to changes in the weighted-average discount rate for our pension plans is as follows:
		U.S. Plans						Non-U.S. Plans
	(In millions)	One Percentage			One Percentage			One Percentage			One Percentage
		Point Increase			Point Decrease			Point Increase			Point Decrease
	Increase (decrease) on projected benefit obligation	$	-41		$	48		$	-149		$	180
	Increase (decrease) on net periodic pension cost		-3			4			-2			5
Summary of Pension Plan Assets Using Fair Value Hierarchy by Asset Class
		U.S. Plans															Non-U.S. Plans
		March 31, 2015															March 31, 2015
	(In millions)	Level 1				Level 2				Level 3			Total				Level 1			Level 2			Level 3		Total
	Cash and cash equivalents	$	55			$	1			$	—		$	56			$	8		$	—		$	—	$	8
	Equity securities:
	Common and preferred stock	18				—				—			18				—			—			—		—
	Equity commingled funds	—				138				—			138				7			149			—		156
	Fixed income securities:
	Government securities	—				14				—			14				26			53			—		79
	Corporate bonds	—				14				—			14				—			13			—		13
	Mortgage-backed securities	—				14				—			14				—			—			—		—
	Asset-backed securities and other	—				26				—			26				—			—			—		—
	Fixed income commingled funds	—				—				—			—				64			127			—		191
	Other:
	Real estate funds	—				—				18			18				—			—			26		26
	Other commingled funds	—				—				—			—				—			13			—		13
	Other	—				—				—			—				7			115			4		126
	Total	$	73			$	207			$	18		$	298			$	112		$	470		$	30	$	612
		U.S. Plans															Non-U.S. Plans
		March 31, 2014															March 31, 2014
	(In millions)	Level 1				Level 2				Level 3			Total				Level 1			Level 2			Level 3		Total
	Cash and cash equivalents	$	8			$	—			$	—		$	8			$	7		$	—		$	—	$	7
	Equity securities:
	Common and preferred stock	19				—				—			19				—			—			—		—
	Equity commingled funds	—				132				—			132				6			157			—		163
	Fixed income securities:
	Government securities	—				7				—			7				4			—			—		4
	Corporate bonds	—				22				—			22				6			236			—		242
	Mortgage-backed securities	—				10				—			10				—			—			—		—
	Asset-backed securities and other	—				22				—			22				—			—			—		—
	Fixed income commingled funds	—				63				—			63				—			45			—		45
	Other:
	Real estate funds	—				—				16			16				—			19			7		26
	Other commingled funds	—				—				—			—				3			49			—		52
	Other	—				—				—			—				—			46			5		51
	Total	$	27			$	256			$	16		299				$	26		$	552		$	12	590
	Receivables (1)												1												—
	Total												$	300											$	590
	-1	Represents pending trades at March 31, 2014
Schedule of Reconciliation of Level 3 Plan Assets Held	The following table represents a reconciliation of Level 3 plan assets held during the years ended March 31, 2015 and 2014:
		U.S. Plans											Non-U.S. Plans
	(In millions)	Real Estate				Other				Total			Real				Other			Total
		Funds											Estate
													Funds
	Balance at March 31, 2013	$	14			$	—			$	14		$	5			$	—		$	5
	Acquisitions	—				—				—			1				5			6
	Unrealized gain on plan assets still held	2				—				2			1				—			1
	Purchases, sales and settlements	—				—				—			—				—			—
	Balance at March 31, 2014	$	16			$	—			$	16		$	7			$	5		$	12
	Acquisitions	—				—				—			—				—			—
	Unrealized gain on plan assets still held	2				—				2			1				—			1
	Purchases, sales and settlements	—				—				—			18				(1		)	17
	Balance at March 31, 2015	$	18			$	—			$	18		$	26			$	4		$	30

Postretirement_Benefits_Tables

Postretirement Benefits (Tables) (Other Postretirement Benefit Plan, Defined Benefit [Member])	12 Months Ended
	Mar. 31, 2015
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Net Periodic Expense (Income) for Postretirement Welfare Benefits	The net periodic expense for our postretirement welfare benefits is as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Service cost - benefits earned during the year	$	1		$	2		$	2
	Interest cost on accumulated benefit obligation	5			5			6
	Amortization of unrecognized actuarial gain and prior service credit	(4		)	(1		)	(2		)
	Curtailment gain	—			(2		)	—
	Net periodic postretirement expense	$	2		$	4		$	6
Schedule of Changes in Benefit Obligations for Postretirement Welfare Plans	Information regarding the changes in benefit obligations for our postretirement welfare plans is as follows:
		Years Ended March 31,
	(In millions)	2015			2014
	Benefit obligation at beginning of period	$	119		$	131
	Service cost	1			2
	Interest cost	5			5
	Actuarial loss (gain)	5			(2		)
	Benefit payments	(12		)	(15		)
	Curtailment gain	—			(2		)
	Benefit obligation at end of period	$	118		$	119

Hedging_Activities_Derivative_

Hedging Activities Derivative Fair Value Table (Tables)	12 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments, Fair Values [Table Text Block]	Information regarding the fair value of derivatives on a gross basis is as follows:
		Balance Sheet	31-Mar-15						31-Mar-14
		Caption	Fair Value of				U.S. Dollar Notional		Fair Value of				U.S Dollar Notional
			Derivative						Derivative
	(In millions)		Asset		Liability				Asset		Liability
	Derivatives designated for hedge accounting
	Foreign exchange	Prepaid expenses and other	$	14	$	—	$	76	$	4	$	—	$	64
	contracts (current)
	Foreign exchange	Other assets	53		—		323		27		—		399
	contracts (non-current)
	Total		$	67	$	—			$	31	$	—
	Derivatives not designated for hedge accounting
	Foreign exchange	Prepaid expenses and other	$	7	$	—	$	493	$	2	$	—	$	255
	contracts (current)
	Foreign exchange	Other accrued liabilities	—		79		1,262		—		13		836
	contracts (current)
	Interest rate swap contracts (current)	Other accrued liabilities	—		—		—		—		1		96
	Total		$	7	$	79			$	2	$	14

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements, Recurring [Table Text Block]	Our financial assets measured at fair value on a recurring basis consist of the following:
		March 31, 2015								March 31, 2014
	(In millions)	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
	Cash Equivalents
	Money market funds (1)	$	2,880	$	—	$	—	$	2,880	$	2,284	$	—	$	—	$	2,284
	Time deposits (2)	—		94		—		94		—		12		—		12
	Repurchase agreements (2)	1,243		—		—		1,243		569		—		—		569
	Total cash equivalents	$	4,123	$	94	$	—	$	4,217	$	2,853	$	12	$	—	$	2,865

Lease_Obligations_Tables

Lease Obligations (Tables)	12 Months Ended
	Mar. 31, 2015
Leases, Operating [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases
	(In millions)	Noncancelable
		Operating
		Leases
	2016	$	316
	2017	271
	2018	219
	2019	170
	2020	140
	Thereafter	650
	Total minimum lease payments (1)	$	1,766

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Schedule of Shares Repurchased Over Last Three Years	Information regarding the share repurchase activity over the last three years is as follows:
		Share Repurchases (1)
	(In millions, except price per share data)		Total		Average Price				Approximate
			Number of		Paid Per Share				Dollar Value of
			Shares						Shares that May
			Purchased (2) (3)						Yet Be Purchased
									Under the
									Programs
	Balance, March 31, 2012								$	299
	Share repurchase plans approved:
	Apr-12								700
	Jan-13								500
	Shares repurchased		13		$	100.82			(1,159		)
	Balance, March 31, 2013								$	340
	Shares repurchased		—		$	—			—
	Balance, March 31, 2014								$	340
	Shares repurchased		1.5		$	226.55			(340		)
	Balance, March 31, 2015								$	—
Schedule of Comprehensive Income (Loss)	Information regarding other comprehensive income (loss) including noncontrolling and redeemable noncontrolling interests, net of tax, by component is as follows:
		Years Ended March 31,
	(In millions)	2015				2014				2013
	Foreign currency translation adjustments
	Foreign currency translation adjustments arising during period, net of income tax expense (benefit) of nil, nil and ($2) (1)	$	(1,845	)		$	9			$	(52	)
	Reclassified to income statement, net of income tax expense of nil, $24 and nil (2)	(10		)		44				—
		(1,855		)		53				(52		)
	Unrealized losses on cash flow hedges
	Unrealized losses on cash flow hedges arising during period, net of income tax benefit of nil, nil and nil	(13		)		(6		)		—
	Reclassified to income statement, net of income tax expense of nil, nil and nil	3				—				—
		(10		)		(6		)		—
	Changes in retirement-related benefit plans
	Net actuarial gain (loss) and prior service credit (cost) arising during period, net of income tax (benefit) of ($66), $16 and ($22)	(140		)		17				(40		)
	Amortization of actuarial loss, prior service cost and transition obligation, net of income tax expense of $6, $12 and $12 (3)	11				22				18
	Foreign currency translation adjustments and other, net of income tax expense of nil, nil and nil	4				(4		)		4
	Reclassified to income statement, net of income tax expense of nil, $1 and nil	1				1				—
		(124		)		36				(18		)
	Other Comprehensive Income (Loss), net of tax	$	(1,989	)		$	83			$	(70	)
Accumulated Other Comprehensive Income	Information regarding changes in our accumulated other comprehensive income (loss) by component are as follows:
	(In millions)	Foreign Currency Translation Adjustments, Net of Tax				Unrealized Losses on Cash Flow Hedges,				Unrealized Net Gains (Losses) and Other Components of Benefit Plans, Net of Tax			Total Accumulated Other Comprehensive Income (Loss)
						Net of Tax
	Balance at March 31, 2013	$	136			$	(5	)		$	(196	)	$	(65	)
	Other comprehensive income (loss) before reclassifications	9				(6		)		35			38
	Amounts reclassified to earnings	44				—				1			45
	Other comprehensive income (loss)	$	53			$	(6	)		$	36		$	83
	Less: other comprehensive income attributable to noncontrolling interests	21				—				—			21
	Other comprehensive income (loss) attributable to McKesson	$	32			$	(6	)		$	36		$	62
	Balance at March 31, 2014	$	168			$	(11	)		$	(160	)	$	(3	)
	Other comprehensive income (loss) before reclassifications	(1,845		)		(13		)		(136		)	(1,994		)
	Amounts reclassified to earnings	(10		)		3				12			5
	Other comprehensive income (loss)	$	(1,855	)		$	(10	)		$	(124	)	$	(1,989	)
	Less: other comprehensive loss attributable to noncontrolling interests	(267		)		—				(12		)	(279		)
	Other comprehensive income (loss) attributable to McKesson	$	(1,588	)		$	(10	)		$	(112	)	$	(1,710	)
	Balance at March 31, 2015	$	(1,420	)		$	(21	)		$	(272	)	$	(1,713	)

Segments_of_Business_Tables

Segments of Business (Tables)	12 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Schedule of Segment Information	Financial information relating to our reportable operating segments and reconciliations to the consolidated totals is as follows:
		Years Ended March 31,
	(In millions)	2015			2014			2013
	Revenues
	Distribution Solutions (1)
	North America pharmaceutical distribution and services	$	143,711		$	123,929		$	115,443
	International pharmaceutical distribution and services	26,358			4,485			—
	Medical-Surgical distribution & services	5,907			5,648			3,603
	Total Distribution Solutions	175,976			134,062			119,046
	Technology Solutions - products and services	3,069			3,330			3,150
	Total Revenues	$	179,045		$	137,392		$	122,196
	Operating profit
	Distribution Solutions	$	3,047		$	2,472		$	2,195
	Technology Solutions	438			448			330
	Total	3,485			2,920			2,525
	Corporate Expenses, Net	(454		)	(449		)	(335		)
	Interest Expense	(374		)	(300		)	(240		)
	Income From Continuing Operations Before Income Taxes	$	2,657		$	2,171		$	1,950
	Depreciation and amortization (2)
	Distribution Solutions	$	750		$	446		$	267
	Technology Solutions	156			169			194
	Corporate	111			120			120
	Total	$	1,017		$	735		$	581
	Expenditures for long-lived assets (3)
	Distribution Solutions	$	301		$	179		$	163
	Technology Solutions	27			47			37
	Corporate	48			52			41
	Total	$	376		$	278		$	241
	Revenues, net by geographic area (4)
	United States	$	142,810		$	122,426		$	112,102
	Foreign	36,235			14,966			10,094
	Total	$	179,045		$	137,392		$	122,196
Segment Assets and Property, Plant and Equipment, Net by Geographic Areas	Segment assets and property, plant and equipment, net by geographic areas were as follows:
		March 31,
	(In millions)	2015			2014
	Segment assets
	Distribution Solutions	$	43,982		$	42,496
	Technology Solutions	3,281			3,573
	Total	47,263			46,069
	Corporate
	Cash and cash equivalents	5,341			4,193
	Other	1,266			1,497
	Total	$	53,870		$	51,759
	Property, plant and equipment, net
	United States	$	1,273		$	1,246
	Foreign	772			950
	Total	$	2,045		$	2,196

Quarterly_Financial_Informatio1

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Mar. 31, 2015													Mar. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information
	(In millions, except per share amounts)	First			Second			Third			Fourth			(In millions, except per share amounts)	First			Second			Third			Fourth
		Quarter			Quarter			Quarter			Quarter				Quarter			Quarter			Quarter			Quarter
	Fiscal 2015													Fiscal 2014
	Revenues	$	43,476		$	44,160		$	46,484		$	44,925		Revenues	$	32,239		$	32,985		$	34,336		$	37,832
	Gross profit (1)	2,732			2,864			2,898			2,917			Gross profit (1)	1,930			2,021			1,850			2,551
	Income after income taxes													Income after income taxes
	Continuing operations (1) (2)	$	419		$	491		$	521		$	411		Continuing operations (1) (2)	$	428		$	423		$	164		$	399
	Discontinued operations (3)	(8		)	(14		)	(10		)	(267		)	Discontinued operations (3)	(4		)	(19		)	(99		)	(34		)
	Net income	411			477			511			144			Net income	424			404			65			365
	Net income attributable to noncontrolling interests (4)	(8		)	(8		)	(39		)	(12		)	Net loss attributable to noncontrolling interests (4)	—			—			—			5
	Net income attributable to McKesson	$	403		$	469		$	472		$	132
														Net income attributable to McKesson	$	424		$	404		$	65		$	370
	Earnings (loss) per common share attributable
	to McKesson (5)													Earnings per common share attributable
	Diluted													to McKesson (5)
	Continuing operations	$	1.76		$	2.05		$	2.04		$	1.69		Diluted
														Continued operations	$	1.84		$	1.82		$	0.7		$	1.72
	Discontinued operations	(0.04		)	(0.06		)	(0.04		)	(1.13		)
	Total	$	1.72		$	1.99		$	2		$	0.56		Discontinued operations	(0.01		)	(0.08		)	(0.42		)	(0.14		)
														Total	$	1.83		$	1.74		$	0.28		$	1.58
	Basic
	Continuing operations	$	1.79		$	2.08		$	2.07		$	1.72		Basic
														Continuing operations	$	1.88		$	1.85		$	0.71		1.76
	Discontinued operations	(0.04		)	(0.06		)	(0.04		)	(1.15		)
	Total	$	1.75		$	2.02		$	2.03		$	0.57		Discontinued operations	(0.02		)	(0.09		)	(0.43		)	(0.15		)
														Total	$	1.86		$	1.76		$	0.28		$	1.61

Significant_Accounting_Policie2

Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Significant Accounting Policies [Line Items]
LIFO inventory, percentage	73.00%	67.00%
LIFO reserve	$768,000,000	$431,000,000
LIFO expense	337,000,000	311,000,000	13,000,000
LIFO inventory, excess of market			60,000,000
LIFO to market adjustment		60,000,000
Capitalized software held for sale, useful life	3 years
Capitalized software held for internal use, net	435,000,000	508,000,000
Capitalized software held for internal use, accumulated amortization	1,112,000,000	1,004,000,000
Sales returns from customers	2,700,000,000	1,900,000,000	1,900,000,000
Supplier reserves	$167,000,000	$181,000,000
Tax benefits recognized from uncertain tax positions, threshold	50.00%
Business combinations, percent consolidated	100.00%
Minimum [Member]
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	1 year
Intangible assets, useful life	1 year
Capitalized software held for internal use, useful life	1 year
Maximum [Member]
Significant Accounting Policies [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
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	44.00%
Accounts Receivable [Member] | Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	36.00%
Largest Customer [Member] | Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	15.00%
Concentration risk, customer name	CVS Caremark Corporation (bCVSb)
Largest Customer [Member] | Accounts Receivable [Member] | Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	14.00%
Concentration risk, customer name	CVS

Business_Combinations_Narrativ

Business Combinations (Narrative) (Details)

12 Months Ended

0 Months Ended

3 Months Ended

12 Months Ended

0 Months Ended

0 Months Ended

12 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2013

Feb. 06, 2014

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2015

Dec. 31, 2014

Feb. 06, 2014

Feb. 22, 2013

Feb. 22, 2013

Apr. 06, 2012

Apr. 06, 2012

Apr. 06, 2012

Mar. 31, 2015

Feb. 22, 2013

USD ($)

USD ($)

USD ($)

Celesio [Member]

Celesio [Member]

Celesio [Member]

Celesio [Member]

Celesio [Member]

Celesio [Member]

PSS World Medical [Member]

PSS World Medical [Member]

Corporate Headquarters [Member]

Corporate Headquarters [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

USD ($)

USD ($)

USD ($)

EUR (€)

EUR (€)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Corporate Headquarters [Member]

Celesio [Member]

PSS World Medical [Member]

USD ($)

USD ($)

USD ($)

Business Acquisition [Line Items]

Effective Date of Acquisition

6-Feb-14

22-Feb-13

6-Apr-12

Percentage of Voting Interests Acquired

77.60%

Name of Acquired Entity

Celesio AG

PSS World Medical, Inc. (bPSSIb)

Per Share Price of Outstanding Shares Acquired

$29

Purchase Price for Acquisition

$1,900,000,000

Cash Paid for Acquisition

4,500,000,000

1,300,000,000

90,000,000

Business Acquisition Percentage Of Voting Interests Acquired Fully Diluted

75.60%

Business Combination, Debt Assumed

2,300,000,000

600,000,000

Description of Acquired Entity

Celesio is an international wholesale and retail company and a provider of logistics and services to the pharmaceutical and healthcare sectors. Celesiobs headquarters is in Stuttgart, Germany and it operates in 14 countries around the world.

PSSI markets and distributes medical products and services throughout the United States.

Debt Conversion, Converted Instrument, Shares Issued

20.9

Convertible bond redemption, cash proceeds

30,000,000

NCI ownership interest, parent

75.40%

Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles

709,000,000

709,000,000

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles

2,309,000,000

3,018,000,000

568,000,000

Annual Recurring Compensation to NCI Under Domination Agreement, Per Share

€ 0.83

Guaranteed Dividend

€ 0.83

Put right price per share

€ 22.99

Put Right Interest Rate

5.00%

Goodwill

9,817,000,000

9,927,000,000

6,405,000,000

4,225,000,000

3,570,000,000

1,149,000,000

Currently Acquired Percentage of Building

50.00%

Previously Held Percentage of Building

50.00%

Gain on business combination

0

0

81,000,000

81,000,000

Business combination gain, after-tax

51,000,000

Net assets, fair value

180,000,000

Building, fair value

113,000,000

Land, fair value

$58,000,000

Business_Combinations_Fair_Val

Business Combinations (Fair Value Of Assets Acquired And Liabilities Assumed) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Feb. 06, 2014
Business Acquisition [Line Items]
Goodwill	$9,817	$9,927	$6,405
Goodwill, Purchase Accounting Adjustments	625	1
Celesio [Member]
Business Acquisition [Line Items]
Receivables	3,376			3,425
Measurement period adjustments, receivables	-49
Other current assets, net of cash and cash equivalents acquired	2,430			2,413
Measurement period adjustments, other current assets, net of cash and cash equivalents acquired	17
Goodwill	4,225			3,570
Goodwill, Purchase Accounting Adjustments	655
Intangible assets	2,309			3,018
Measurement period adjustments, intangible assets	-709
Other long-term assets	1,233			1,272
Measurement period adjustments, other long-term assets	-39
Current liabilities	-4,124			-4,096
Measurement period adjustments, current liabilities	-28
Short-term borrowings and current portion of long-term debt	-1,990			-1,990
Measurement period adjustments, short-term borrowings	0
Long-term debt	-322			-322
Measurement period adjustments, long-term debt	0
Other long-term liabilities	-1,135			-1,293
Measurement period adjustments, other long-term liabilities	158
Fair value of net assets, less cash and cash equivalents	6,002			5,997
Measurement period adjustments, fair value of net assets	5
Less: Noncontrolling interests	-1,505			-1,500
Measurement period adjustments, less: noncontrolling interest	-5
Net assets acquired, net of cash and cash equivalents	4,497			4,497
Measurement period adjustments, net assets acquired, net of cash and cash equivalents	$0

Noncontrolling_Interests_Nonco1

Noncontrolling Interests Noncontrolling Interests (Ownership Changes) (Narrative) (Details)	12 Months Ended	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
	USD ($)	Celesio [Member]	Celesio [Member]	Celesio [Member]	Celesio [Member]
		USD ($)	USD ($)	EUR (€)
Noncontrolling Interest [Line Items]
NCI ownership interest, parent		76.00%			75.40%
NCI shares acquired, cash paid		$8	$32
NCI shares acquired		0.3	1
Tender offer price per share				€ 23.50
NCI shares acquired, change in ownership percentage			0.50%
NCI change from shares acquired	62	9	35
NCI shares acquired, change in APIC	2
NCI shares acquired, change in parent net income and transfers to NCI	$1,474

Noncontrolling_Interests_Nonco2

Noncontrolling Interests Noncontrolling Interests (Changes in Noncontrolling Interests) (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2015
Noncontrolling Interest [Line Items]
Balance, March 31, 2014		$1,796	$1,796
NCI change from shares acquired			-62
Reclassification from total equity to redeemable noncontrolling interests			-1,500
Noncontrolling interests, ending balance	84		84
Celesio [Member]
Noncontrolling Interest [Line Items]
Other comprehensive income, NCI portion			-138
NCI change from shares acquired	($9)	($35)

Noncontrolling_Interests_Redee

Noncontrolling Interests Redeemable Noncontrolling Interests (Narrative) (Details)	12 Months Ended		3 Months Ended		9 Months Ended	12 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Jun. 30, 2014	Dec. 31, 2014	Mar. 31, 2015	Mar. 31, 2015	Mar. 31, 2014
	USD ($)	USD ($)	Celesio [Member]	Celesio [Member]	Celesio [Member]	Celesio [Member]	Celesio [Member]	Celesio [Member]
			USD ($)	USD ($)	USD ($)	USD ($)	EUR (€)	USD ($)
Redeemable Noncontrolling Interest [Line Items]
Guaranteed dividend amount			$12,000,000		$50,000,000
RNCI, recurring compensation per share							€ 0.83
Net income attributable to redeemable NCI						62,000,000
Reclassification from permanent to temporary equity					1,500,000,000	1,500,000,000
RNCI shares acquired, cash paid			8,000,000	32,000,000
RNCI shares acquired			0.3	1
NCI change from shares acquired	-62,000,000		-9,000,000	-35,000,000
Redeemable Noncontrolling Interests	1,386,000,000	0	1,400,000,000			1,400,000,000		0
RNCI, redemption value			1,200,000,000			1,200,000,000
Recurring compensation to redeemable NCI			$12,000,000
RNCI ownership interest, parent			76.00%			76.00%		75.40%

Noncontrolling_Interests_Redee1

Noncontrolling Interests Redeemable Noncontrolling Interests (Rollforward) (Details) (USD $)	12 Months Ended	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2015	Jun. 30, 2014	Dec. 31, 2014	Mar. 31, 2014
Redeemable Noncontrolling Interest [Line Items]
Noncontrolling Interests	$84	$84			$1,796
NCI, carrying value, beginning balance	0		0	0
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent	62
Reclassification from Permanent Equity	1,500
NCI, carrying value, ending balance	1,386	1,386
Celesio [Member]
Redeemable Noncontrolling Interest [Line Items]
NCI, carrying value, beginning balance	0		0	0
Redeemable NCI, net income	62
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	138
Redeemable NCI, translation adjustments	-105
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent		9	35
Redeemable NCI, purchase of interests	-9
Reclassification from permanent to temporary equity	1,500			1,500
Reclassification of temporary equity to liability	-62
Redeemable NCI, other changes	0
NCI, carrying value, ending balance	1,400	1,400
Noncontrolling Interest [Member]
Redeemable Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interests Excluding Redeemable Noncontrolling Interests	5
Noncontrolling Interests					1,796
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	174
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent	60
Reclassification from Permanent Equity	1,500
Reclassification from Equity to Liability	0
Noncontrolling Interests, Changes, Other	($17)

Discontinued_Operations_Narrat

Discontinued Operations (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2014	Mar. 31, 2015	Jun. 30, 2014
Discontinued Operations Disclosures
Asset fair value adjustment	$241	$80
Gain (loss) on disposal, pre-tax	-6	-5	0
Accumulated other comprehensive income (loss), currency translation adjustment	-1,713	-3			-1,713
Assets held for sale	660				660
Liabilities held for sale	663				663
International Technology, Software [Member]
Discontinued Operations Disclosures
Gain (loss) on disposal, pre-tax				-6
Gain (loss) on disposal, net of tax				-6
Brazil Distribution [Member]
Discontinued Operations Disclosures
Impairment charges					241
Impairment charges, net of tax					235
Impairment of long-lived assets to be disposed					31
Impairment in excess of carrying value, liability amount	210				210
Accumulated other comprehensive income (loss), currency translation adjustment	17				17
Hospital Automation [Member]
Discontinued Operations Disclosures
Gain (loss) on disposal, pre-tax		-5
Gain (loss) on disposal, net of tax		-7
Proceeds from sale		55
International Technology [Member]
Discontinued Operations Disclosures
Impairment charges		80
Impairment charges, net of tax		80
Cost of Sales [Member] | International Technology, Workforce [Member]
Discontinued Operations Disclosures
Asset fair value adjustment						34
Asset fair value adjustment, net of tax						$27

Discontinued_Operations_Discon1

Discontinued Operations Discontinued Operations (Schedule of Results from Discontinued Operations) (Details) (USD $)	3 Months Ended										12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Discontinued Operations and Disposal Groups [Abstract]
Revenues											$2,196	$637	$259
Loss from discontinued operations											-321	-177	-32
Loss on sale											-6	-5	0
Loss from discontinued operations before income tax											-327	-182	-32
Income tax benefit											28	26	7
Income (Loss) from Discontinued Operations, Net of Tax	($267)	[1]	($10)	($14)	($8)	($34)	($99)	[2]	($19)	($4)	($299)	($156)	($25)
[1]	Fourth quarter of 2015 includes $235 million non-cash after-tax impairment charges related to our Brazilian pharmaceutical distribution business.
[2]	Financial results for the third quarter of 2014 include an $80 million after-tax impairment charge related to our International Technology Business, which was sold in part during the second quarter of 2015.

Asset_Impairments_and_Product_1

Asset Impairments and Product Alignment Charges (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Asset Impairments And Product Alignment Charges [Line Items]
Capitalized software held for sale impairment	$0	$12	$10
Technology Solutions [Member]
Asset Impairments And Product Alignment Charges [Line Items]
Nonrecurring charges		57	46
Product alignment charges		35
Integration related costs		15
Reduction in force severance charges		7
Asset impairment charges		15
Technology Solutions [Member] | Cost of Sales [Member]
Asset Impairments And Product Alignment Charges [Line Items]
Nonrecurring charges		34
Capitalized software held for sale impairment			10
Technology Solutions [Member] | Operating Expense [Member]
Asset Impairments And Product Alignment Charges [Line Items]
Nonrecurring charges		23
Goodwill impairment			36
Technology Solutions [Member] | Severance Charges Due to Reorganization [Member]
Asset Impairments And Product Alignment Charges [Line Items]
Reduction in force severance charges		$35

Equity_Investments_Narrative_D

Equity Investments (Narrative) (Details) (USD $)	12 Months Ended			6 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013
Schedule of Equity Method Investments [Line Items]
Impairment of an equity investment	$0	$0	$191
Distribution Solutions [Member] | Brocacef [Member]
Schedule of Equity Method Investments [Line Items]
Equity interest in investee	45.00%
Distribution Solutions [Member] | Nadro [Member]
Schedule of Equity Method Investments [Line Items]
Equity interest in investee		49.00%	49.00%	49.00%
Impairment of an equity investment			191
Cumulative foreign currency translation losses			69
Proceeds from sale of equity investments				$41

ShareBased_Compensation_Narrat

Share-Based Compensation (Narrative) (Details)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vested and exercisable, shares	2,000,000
Expected dividend yield	0.60%	0.70%	0.90%
Risk free interest rate	1.30%	0.70%	0.80%
Expected stock price volatility rate	22.00%	22.00%	27.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock award contractual term	7 years
Stock award vesting period	4 years
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock award vesting period	3 years
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock award vesting period	4 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock award vesting period	4 years
Market-Based Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock award contractual term	3 years
Stock award vesting period	3 years
Expected dividend yield	0.50%
Risk free interest rate	0.70%
Expected stock price volatility rate	21.30%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	21,000,000
Number of shares available for grant	5,000,000
Period over which payoll is deducted to purchase shares	3 months
Percentage of market price for share purchase	85.00%
Percentage of market price deduction for share purchases	15.00%
Shares issued under ESPP			1,000,000
2013 Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	30,000,000
Number of shares available for grant	30,000,000
Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vested and exercisable, shares	158,000

ShareBased_Compensation_Compon

Share-Based Compensation (Components of Share-Based Compensation Expense) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$174		$160		$167
Tax benefit for share-based compensation expense	-61	[1]	-55	[1]	-59	[1]
Share-based compensation expense, net of tax	113		105		108
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	137	[2]	126	[2]	132	[2]
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	24		22		24
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$13		$12		$11
[1]	Income tax benefit is computed using the tax rates of applicable tax jurisdictions. Additionally, a portion of pre-tax compensation expense is not tax-deductible.
[2]	RSUs, PeRSUs and TSRUs. Our TSRUs were awarded beginning in 2015.

ShareBased_Compensation_Schedu

Share-Based Compensation (Schedule of Assumptions for Stock Options Fair Values) (Details)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation [Abstract]
Expected stock price volatility rate	22.00%	22.00%	27.00%
Expected dividend yield	0.60%	0.70%	0.90%
Risk free interest rate	1.30%	0.70%	0.80%
Expected life	4 years	4 years	5 years

ShareBased_Compensation_Summar

Share-Based Compensation (Summary of Options Outstanding) (Details) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding	5
Options exercisable	2
$40.46 - $133.27 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range lower limit	$40.46
Exercise price range upper limit	$133.27
Options outstanding	4
Remaining contractual life, weighted average	3 years
Exercise price, weighted average	$79.38
Options exercisable	2
Exercise price, weighted average	$68.80
$133.28 - $226.05 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range lower limit	$133.28
Exercise price range upper limit	$226.05
Options outstanding	1
Remaining contractual life, weighted average	6 years
Exercise price, weighted average	$182.38
Options exercisable	0
Exercise price, weighted average	$155.87

ShareBased_Compensation_Stock_

Share-Based Compensation (Stock Option Activity) (Details) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Share-based Compensation [Abstract]
Stock options outstanding	5		6
Stock options granted	1
Stock options exercised	-2
Stock options vested and expected to vest	5	[1]
Stock options vested and exercisable	2
Stock options outstanding, weighted-average exercise price	$95.01		$78.07
Stock options granted, weighted-average exercise price	$184.84
Stock options exercised, weighted-average exercise price	$67.64
Stock options vested and expected to vest, exercise price	$95.01	[1]
Stock options vested and exercisable, exercise price	$69.27
Stock options outstanding, remaining contractual term	4 years		4 years
Stock options vested and expected to vest, remaining contractual term	4 years	[1]
Stock options vested and exercisable, remaining contractual term	3 years
Stock options outstanding, intrinsic value	$539	[2]	$473	[2]
Stock options vested and expected to vest, intrinsic value	538	[1],[2]
Stock options vested and exercisable, intrinsic value	$363	[2]
[1]	The number of options expected to vest takes into account an estimate of expected forfeitures.
[2]	The intrinsic value is calculated as the difference between the period-end market price of the Companybs common stock and the exercise price of bin-the-moneyb options.

ShareBased_Compensation_Data_R

Share-Based Compensation (Data Related to Stock Option Activity) (Details) (Stock Options [Member], USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value	$35.49	$21.45	$19.63
Aggregate intrinsic value on exercise	$153	$144	$107
Cash received upon exercise	76	111	106
Tax benefits realized related to exercise	60	55	41
Total fair value of shares vested	20	24	24
Total compensation cost, net of estimated forfeitures, related to nonvested awards not yet recognized, pre-tax	$22	$29	$37
Weighted-average period in years over which stock award cost is expected to be recognized	2 years	1 year	1 year

ShareBased_Compensation_RSU_Ac

Share-Based Compensation (RSU Activity) (Details) (Restricted Stock Units (RSUs) [Member], USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units nonvested	4	4
Restricted stock units granted	1
Restricted stock units vested	-1
Restricted stock units nonvested, grant date fair value	$129.57	$93.25
Restricted stock units granted, grant date fair value	$187.03
Restricted stock units vested, grant date fair value	$84.28

ShareBased_Compensation_Data_R1

Share-Based Compensation (Data Related to RSU Activity) (Details) (Restricted Stock Units (RSUs) [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of shares vested	$126	$184	$66
Total compensation cost, net of estimated forfeitures, related to nonvested awards not yet recognized, pre-tax	$206	$236	$210
Weighted-average period in years over which stock award cost is expected to be recognized	2 years	2 years	2 years

Other_Income_Expense_Net_Summa

Other Income (Expense), Net (Summary of Other Income (Expense), Net) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Other Nonoperating Income (Expense) [Abstract]
Interest income	$20		$16		$22
Equity in earnings (loss), net (1)	12	[1]	0	[1]	3	[1]
Other, net (1)	31	[1]	16	[1]	9	[1]
Total	$63		$32		$34
[1]	Primarily recorded within our Distribution Solutions segment.

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2012
Income Tax Contingency [Line Items]
Income tax expense	$815	$757	$587
Income tax benefit (expense) discrete items	33	-94	29
Undistributed Earnings of Foreign Operations	4,916
Deferred Tax Liabilities, Undistributed Foreign Earnings	0
Unrecognized Tax Benefits	616	647	560		595
Unrecognized Tax Benefits that would Impact Income Tax Expense and the Effective Tax Rate	457
Potential Reduction of Unrecognized Benefits Due to Audit Resolutions and Expiration of Statutes of Limitations	137
Income Tax Expense (Benefit), Before Any Tax Effect, Related to Accrued Interest	-24	48
Accrued interest and penalties on unrecognized tax benefits	122	179
Canada Revenue Agency Assessments [Member]
Income Tax Contingency [Line Items]
Income tax benefit (expense) discrete items		122		122
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Income tax benefit (expense) discrete items	55
Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Federal, State and Foreign Operating Loss Carryforwards	44
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Federal, State and Foreign Operating Loss Carryforwards	1,930
Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Federal, State and Foreign Operating Loss Carryforwards	$711

Income_Taxes_Income_From_Conti

Income Taxes (Income From Continuing Operations Before Income Taxes) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]
U.S.	$1,893	$1,554	$1,562
Foreign	764	617	388
Total income from continuing operations before income taxes	$2,657	$2,171	$1,950

Income_Taxes_Components_Of_Pro

Income Taxes (Components Of Provision For Income Taxes Related To Continuing Operations) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]
Federal	$453	$484	($84)
State	90	64	14
Foreign	101	193	46
Total current	644	741	-24
Federal	195	24	538
State	53	10	80
Foreign	-77	-18	-7
Total deferred	171	16	611
Income tax expense	$815	$757	$587

Income_Taxes_Reconciliation_Be

Income Taxes (Reconciliation Between Effective Tax Rate On Income From Continuing Operations And Statutory Tax Rate) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]
Income tax expense at federal statutory rate	$930	$760	$683
State income taxes net of federal tax benefit	81	57	58
Foreign income taxed at various rates	-247	-177	-143
Canadian litigation	0	122	0
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Amount	58	0	0
Unrecognized tax benefits and settlements	10	-6	1
Tax credits	-10	-6	-13
Other, net	-7	7	1
Income tax expense	$815	$757	$587

Income_Taxes_Components_Of_Def

Income Taxes (Components Of Deferred Tax Balances) (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014
In Millions, unless otherwise specified
Income Tax Disclosure [Abstract]
Receivable allowances	$83	$94
Deferred revenue	72	136
Compensation and benefit related accruals	681	632
Net operating loss and credit carryforwards	316	337
Other	266	287
Subtotal	1,418	1,486
Less: valuation allowance	-229	-200
Total assets	1,189	1,286
Inventory valuation and other assets	-2,333	-2,161
Fixed assets and systems development costs	-324	-320
Intangibles	-1,073	-1,477
Other	-61	-117
Total liabilities	-3,791	-4,075
Net deferred tax liability	-2,602	-2,789
Current net deferred tax asset	26	42
Current net deferred tax liability	-1,819	-1,588
Long-term deferred tax asset	50	19
Long-term deferred tax liability	($859)	($1,262)

Income_Taxes_Gross_Unrecognize

Income Taxes (Gross Unrecognized Tax Benefits) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]
Unrecognized tax benefits at beginning of period	$647	$560	$595
Additions based on tax positions related to prior years	62	106	46
Reductions based on tax positions related to prior years	-18	-23	-106
Additions based on tax positions related to current year	27	23	31
Reductions based on settlements	-65	-4	-2
Reductions based on the lapse of the applicable statutes of limitations	-12	-7	-2
Unrecognized Tax Benefits, Decrease Resulting from Foreign Currency Translation	-25	-8	-2
Unrecognized tax benefits at end of period	$616	$647	$560

Earnings_Per_Common_Share_Narr

Earnings Per Common Share (Narrative) (Details)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]
Potentially dilutive shares excluded from diluted earnings per share	1	2	2

Earnings_Per_Common_Share_Basi

Earnings Per Common Share (Basic and Diluted Earnings per Common Share) (Details) (USD $)	3 Months Ended																12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income from continuing operations	$411	[1],[2]	$521	[1]	$491	[1]	$419	[1]	$399	[3],[4]	$164	[3],[4]	$423	[3]	$428	[3]	$1,842		$1,414		$1,363
Net loss (income) attributable to noncontrolling interests	-12	[5]	-39	[5]	-8	[5]	-8	[5]	5	[6]	0	[6]	0	[6]	0	[6]	-67		5		0
Income from continuing operations attributable to McKesson																	1,775		1,419		1,363
Income (Loss) from Discontinued Operations, Net of Tax	-267	[7]	-10		-14		-8		-34		-99	[8]	-19		-4		-299		-156		-25
Net Income Attributable to McKesson	$132		$472		$469		$403		$370		$65		$404		$424		$1,476		$1,263		$1,338
Weighted average common shares outstanding:
Basic																	232		229		235
Effect of dilutive securities:
Diluted																	235		233		239
Diluted
Continuing operations	$1.69	[9]	$2.04	[9]	$2.05	[9]	$1.76	[9]	$1.72	[9]	$0.70	[9]	$1.82	[9]	$1.84	[9]	$7.54	[9]	$6.08	[9]	$5.69	[9]
Discontinued operations	($1.13)	[9]	($0.04)	[9]	($0.06)	[9]	($0.04)	[9]	($0.14)	[9]	($0.42)	[9]	($0.08)	[9]	($0.01)	[9]	($1.27)	[9]	($0.67)	[9]	($0.10)	[9]
Total	$0.56	[9]	$2	[9]	$1.99	[9]	$1.72	[9]	$1.58	[9]	$0.28	[9]	$1.74	[9]	$1.83	[9]	$6.27	[9]	$5.41	[9]	$5.59	[9]
Basic
Continuing operations	$1.72	[9]	$2.07	[9]	$2.08	[9]	$1.79	[9]	$1.76	[9]	$0.71	[9]	$1.85	[9]	$1.88	[9]	$7.66	[9]	$6.19	[9]	$5.81	[9]
Discontinued operations	($1.15)	[9]	($0.04)	[9]	($0.06)	[9]	($0.04)	[9]	($0.15)	[9]	($0.43)	[9]	($0.09)	[9]	($0.02)	[9]	($1.29)	[9]	($0.68)	[9]	($0.10)	[9]
Total	$0.57	[9]	$2.03	[9]	$2.02	[9]	$1.75	[9]	$1.61	[9]	$0.28	[9]	$1.76	[9]	$1.86	[9]	$6.37	[9]	$5.51	[9]	$5.71	[9]
Stock Options [Member]
Effect of dilutive securities:
Options to purchase common stock																	1		1		1
Restricted Stock Units (RSUs) [Member]
Effect of dilutive securities:
Options to purchase common stock																	2		3		3
[1]	Financial results for the first, second, third and fourth quarters of 2015 include pre-tax charges in our Distribution Solutions segment related to our last-in-first-out (bLIFOb) method of accounting for inventories of $98 million, $94 million, $95 million and $50 million, which were recorded in cost of sales.
[2]	Fourth quarter of 2015 includes a non-cash after-tax charge of $150 million related to the settlement of controlled substance distribution claims.
[3]	Financial results for the second, third and fourth quarters of 2014 include pre-tax charges in our Distribution Solutions segment related to our LIFO method of accounting for inventories of $44 million, $142 million and $125 million, which were recorded in cost of sales. The fourth quarter of 2014 also includes a $40 million pre-tax charge to cost of sales within our Distribution Solutions segment representing the reversal of a step-up to fair value of Celesiobs inventory at the date of acquisition. Our after-tax portion of this charge from continuing operations (after allocation to noncontrolling interests) was $21 million.
[4]	Financial results for the third quarter of 2014 include an income tax charge of $122 million relating to our litigation with the Canadian Revenue Agency.
[5]	Primarily reflects the guaranteed dividends of $50 million for the first nine months of 2015 and the recurring compensation of $12 million for the fourth quarter of 2015. McKesson is obligated to pay these amounts to the noncontrolling shareholders of Celesio under the Domination Agreement which became effective in December 2014.
[6]	Primarily represents the noncontrolling shareholdersb portion of net loss from Celesio.
[7]	Fourth quarter of 2015 includes $235 million non-cash after-tax impairment charges related to our Brazilian pharmaceutical distribution business.
[8]	Financial results for the third quarter of 2014 include an $80 million after-tax impairment charge related to our International Technology Business, which was sold in part during the second quarter of 2015.
[9]	Certain computations may reflect rounding adjustments.

Receivables_Net_Schedule_of_Ac

Receivables, Net (Schedule of Accounts Receivable) (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014
In Millions, unless otherwise specified
Receivables, Net, Current [Abstract]
Customer accounts	$13,117	$12,169
Other	2,965	1,740
Total	16,082	13,909
Allowances	-168	-129
Net	$15,914	$13,780

Property_Plant_and_Equipment_N2

Property, Plant and Equipment, Net (Schedule Of Property, Plant And Equipment, Net) (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014
In Millions, unless otherwise specified
Property, Plant and Equipment, Net [Abstract]
Land	$207	$221
Building, machinery, equipment and other	3,237	3,155
Total property, plant and equipment	3,444	3,376
Accumulated depreciation	-1,399	-1,180
Property, plant and equipment, net	$2,045	$2,196

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets, Net (Narrative - Goodwill) (Details) (Technology Solutions [Member], USD $)	Mar. 31, 2015	Mar. 31, 2014
In Millions, unless otherwise specified
Technology Solutions [Member]
Goodwill [Line Items]
Accumulated goodwill impairment	$36	$36

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets, Net (Narrative - Intangible Assets) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization Expense of Intangible Assets	$494	$319	$215
Annual Amortization Expense, 2016	419
Annual Amortization Expense, 2017	389
Annual Amortization Expense, 2018	360
Annual Amortization Expense, 2019	332
Annual Amortization Expense, 2020	303
Annual Amortization Expense, After 2020	$1,638

Goodwill_and_Intangible_Assets4

Goodwill and Intangible Assets, Net (Changes In The Carrying Amount Of Goodwill) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Goodwill [Line Items]
Goodwill, beginning balance	$9,927	$6,405
Goodwill acquired	93	3,649
Amount reclassified to assets held-for-sale	-15	-128
Acquisition accounting, transfers and other adjustments	625	1
Foreign currency translation adjustments, net	-813	0
Goodwill, ending balance	9,817	9,927
Distribution Solutions [Member]
Goodwill [Line Items]
Goodwill, beginning balance	8,078	4,413
Goodwill acquired	93	3,649
Amount reclassified to assets held-for-sale	-14	-1
Acquisition accounting, transfers and other adjustments	625	13
Foreign currency translation adjustments, net	-788	4
Goodwill, ending balance	7,994	8,078
Technology Solutions [Member]
Goodwill [Line Items]
Goodwill, beginning balance	1,849	1,992
Goodwill acquired	0	0
Amount reclassified to assets held-for-sale	-1	-127
Acquisition accounting, transfers and other adjustments	0	-12
Foreign currency translation adjustments, net	-25	-4
Goodwill, ending balance	$1,823	$1,849

Goodwill_and_Intangible_Assets5

Goodwill and Intangible Assets, Net (Information Regarding Intangible Assets) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$5,204	$6,201
Accumulated Amortization	-1,763	-1,330
Net Carrying Amount	3,441	4,871
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period (years)	8 years
Gross Carrying Amount	2,683	3,235
Accumulated Amortization	-1,116	-863
Net Carrying Amount	1,567	2,372
Service Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period (years)	15 years
Gross Carrying Amount	957	995
Accumulated Amortization	-215	-173
Net Carrying Amount	742	822
Pharmacy Licenses [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period (years)	26 years
Gross Carrying Amount	874	1,219
Accumulated Amortization	-65	-11
Net Carrying Amount	809	1,208
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period (years)	15 years
Gross Carrying Amount	315	367
Accumulated Amortization	-82	-59
Net Carrying Amount	233	308
Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period (years)	3 years
Gross Carrying Amount	213	219
Accumulated Amortization	-184	-173
Net Carrying Amount	29	46
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period (years)	4 years
Gross Carrying Amount	162	166
Accumulated Amortization	-101	-51
Net Carrying Amount	$61	$115

Capitalized_Software_Held_for_2

Capitalized Software Held for Sale (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Capitalized Computer Software, Net [Abstract]
Royalty fees paid	$91	$91	$88

Capitalized_Software_Held_for_3

Capitalized Software Held for Sale (Changes in the Carrying Amount) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Capitalized Computer Software, Net [Abstract]
Capitalized software held for sale, net at beginning of period	$103	$126	$144
Amounts capitalized	34	40	49
Amortization expense	-40	-50	-56
Impairment charges	0	-12	-10
Foreign currency translations adjustments, net	-6	-1	-1
Capitalized software held for sale, net at end of period	$91	$103	$126

Debt_and_Financing_Activities_1

Debt and Financing Activities (Long-Term Debt) (Narrative) (Details) (USD $)	0 Months Ended		1 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 05, 2014	Dec. 04, 2012	Mar. 31, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
				D
Debt Instrument [Line Items]
Proceeds from issuances of long-term debt	$4,068	$892	$891	$3	$4,124	$1,798
Days notice for redemption prior to maturity				30
Redemption purchase offer				101.00%
Long-term debt				9,709	10,346
Future principal payments of long-term debt in 2016					1,529
Future principal payments of long-term debt in 2017					1,619
Future principal payments of long-term debt in 2018					1,086
Future principal payments of long-term debt in 2019					1,474
Future principal payments of long-term debt in 2020					19
Future principal payments of long-term debt, thereafter					3,982
Floating Rate Notes Due September 10, 2015 [Member]
Debt Instrument [Line Items]
Debt face value					400
Debt variable interest rate				0.66%
Debt maturity date				10-Sep-15	10-Sep-15
Long-term debt				400	400
1.29% Notes Due March 10, 2017 [Member]
Debt Instrument [Line Items]
Debt face value					700
Debt interest rate				1.29%	1.29%
Debt maturity date				10-Mar-17	10-Mar-17
Long-term debt				700	700
2.28% Notes Due March 15, 2019 [Member]
Debt Instrument [Line Items]
Debt face value					1,100
Debt interest rate				2.28%	2.28%
Debt maturity date				15-Mar-19	15-Mar-19
Long-term debt				1,100	1,100
3.80% Notes Due March 15, 2024 [Member]
Debt Instrument [Line Items]
Debt face value					1,100
Debt interest rate				3.80%	3.80%
Debt maturity date				15-Mar-24	15-Mar-24
Long-term debt				1,100	1,100
4.88% Notes Due March 15, 2044 [Member]
Debt Instrument [Line Items]
Debt face value					800
Debt interest rate				4.88%	4.88%
Debt maturity date				15-Mar-44	15-Mar-44
Long-term debt				800	800
1.40% Notes Due March 15, 2018 [Member]
Debt Instrument [Line Items]
Debt face value			500			500
Debt interest rate			1.40%	1.40%	1.40%	1.40%
Debt maturity date				15-Mar-18	15-Mar-18	15-Mar-18
Long-term debt				499	499
2.85% Notes Due March 15, 2023 [Member]
Debt Instrument [Line Items]
Debt face value			400			400
Debt interest rate			2.85%	2.85%	2.85%	2.85%
Debt maturity date				15-Mar-23	15-Mar-23	15-Mar-23
Long-term debt				400	400
0.95% Notes Due December 4, 2015 [Member]
Debt Instrument [Line Items]
Debt face value			500			500
Debt interest rate			0.95%	0.95%	0.95%	0.95%
Debt maturity date				4-Dec-15	4-Dec-15	4-Dec-15
Long-term debt				500	499
2.70% Notes Due December 15, 2022 [Member]
Debt Instrument [Line Items]
Debt face value			400			400
Debt interest rate			2.70%	2.70%	2.70%	2.70%
Debt maturity date				15-Dec-22	15-Dec-22	15-Dec-22
Long-term debt				400	400
6.50% Notes Due February 15, 2014 [Member]
Debt Instrument [Line Items]
Debt interest rate					6.50%
Debt repayment amount					350
5.25% Notes Due March 1, 2013 [Member]
Debt Instrument [Line Items]
Debt interest rate					5.25%
Debt repayment amount					500
4.00% Bonds Due October 18, 2016 [Member]
Debt Instrument [Line Items]
Debt interest rate				4.00%	4.00%
Debt maturity date				18-Oct-16	18-Oct-16
Long-term debt				388	507
4.50% Bonds Due April 26, 2017 [Member]
Debt Instrument [Line Items]
Debt interest rate				4.50%	4.50%
Debt maturity date				26-Apr-17	26-Apr-17
Long-term debt				563	737
4.00% Bonds Due October 18, 2016 and 4.50% Bonds Due April 26, 2017 [Member]
Debt Instrument [Line Items]
Long-term debt				951	1,244
Promissory Notes [Member]
Debt Instrument [Line Items]
Long-term debt				0	297
Term Loan [Member]
Debt Instrument [Line Items]
Debt variable interest rate				1.93%
Debt maturity date				15-Dec-19
Long-term debt				89	100
Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt interest rate			6.38%			6.38%
Debt maturity date						31-Jan-22
Senior Convertible Notes Due 2014 [Member]
Debt Instrument [Line Items]
Debt interest rate				3.13%
Debt maturity date						30-Nov-14
Senior Notes Due 2022 And Senior Convertible Notes Due 2014 [Member]
Debt Instrument [Line Items]
Debt repayment amount						$643
London Interbank Offered Rate (LIBOR) [Member] | Floating Rate Notes Due September 10, 2015 [Member]
Debt Instrument [Line Items]
Debt variable interest rate					0.40%

Recovered_Sheet1

Debt And Financing Activities (Senior Bridge Term Loan Facility) (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended
	Jan. 31, 2014	Mar. 31, 2014	Mar. 31, 2013	Feb. 28, 2013	Dec. 31, 2012
Senior Bridge Term Loan Agreement, 2014 [Member]
Debt Instrument [Line Items]
Credit facility borrowing capacity	$5,500,000,000
Credit facility expiration period	364 days
Proceeds from lines of credit		4,957,000,000
Repayments of lines of credit		4,076,000,000
Credit facility interest rate		1.39%
Debt issuance costs		46,000,000
Senior Bridge Term Loan Agreement, 2013 [Member]
Debt Instrument [Line Items]
Credit facility borrowing capacity				900,000,000	2,100,000,000
Proceeds from lines of credit			900,000,000
Repayments of lines of credit			900,000,000
Credit facility interest rate			1.20%
Debt issuance costs			$11,000,000

Recovered_Sheet2

Debt And Financing Activities (Accounts Receivable Facilities, Revolving Credit Facilities and Lines of Credit) (Narrative) (Details)

12 Months Ended

12 Months Ended

12 Months Ended

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2014

Bilateral Lines of Credit [Member]

Bilateral Lines of Credit [Member]

Accounts Receivable Sales Facility [Member]

Accounts Receivable Sales Facility [Member]

Accounts Receivable Sales Facility [Member]

Accounts Receivable Factoring Facility [Member]

Accounts Receivable Factoring Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Foreign Line of Credit [Member]

Celesio [Member]

Celesio [Member]

Celesio [Member]

Floating Rate Notes Due September 10, 2015 [Member]

Floating Rate Notes Due September 10, 2015 [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

USD ($)

USD ($)

EUR (€)

Line of Credit Facility [Line Items]

Debt maturity date

10-Sep-15

10-Sep-15

Credit facility expiration period

2 years

Credit facility borrowing capacity

$1,400,000,000

$1,350,000,000

$169,000,000

$1,300,000,000

€ 500,000,000

Credit facility expiration date

30-Nov-16

31-Jan-16

23-Sep-16

28-Feb-18

Proceeds from lines of credit

225,000,000

0

550,000,000

1,325,000,000

2,875,000,000

570,000,000

0

0

0

0

0

0

Repayments of lines of credit

267,000,000

0

550,000,000

1,725,000,000

2,908,000,000

575,000,000

Other Short-term Borrowings

29,000,000

65,000,000

0

0

135,000,000

246,000,000

Pledged Assets, Not Separately Reported, Finance Receivables

0

0

135,000,000

246,000,000

Credit facility outstanding, long-term

$0

$0

$0

$0

$0

Interest rate, minimum

0.20%

0.85%

Interest rate, maximum

6.00%

1.26%

Debt_And_Financing_Activities_2

Debt And Financing Activities (Commericial Paper and Debt Covenants) (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]
Commercial paper issuances	$0	$0	$0
Commercial paper outstanding	0	0
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility borrowing capacity	1,300
Accounts Receivable Sales Facility [Member]
Debt Instrument [Line Items]
Credit facility borrowing capacity	$1,350
Maximum [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt to capital ratio	0.65

Debt_And_Financing_Activities_3

Debt And Financing Activities (Schedule Of Long-Term Debt) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]
Long-term debt	$9,709	$10,346
Less current portion	-1,529	-1,417
Total long-term debt	8,180	8,929
Floating Rate Notes Due September 10, 2015 [Member]
Debt Instrument [Line Items]
Long-term debt	400	400
Debt variable interest rate	0.66%
Debt maturity date	10-Sep-15	10-Sep-15
0.95% Notes Due December 4, 2015 [Member]
Debt Instrument [Line Items]
Long-term debt	500	499
Debt interest rate	0.95%	0.95%	0.95%
Debt maturity date	4-Dec-15	4-Dec-15	4-Dec-15
3.25% Notes Due March 1, 2016 [Member]
Debt Instrument [Line Items]
Long-term debt	600	599
Debt interest rate	3.25%	3.25%
Debt maturity date	1-Mar-16	1-Mar-16
5.70% Notes Due March 1, 2017 [Member]
Debt Instrument [Line Items]
Long-term debt	500	500
Debt interest rate	5.70%	5.70%
Debt maturity date	1-Mar-17	1-Mar-17
1.29% Notes Due March 10, 2017 [Member]
Debt Instrument [Line Items]
Long-term debt	700	700
Debt interest rate	1.29%	1.29%
Debt maturity date	10-Mar-17	10-Mar-17
1.40% Notes Due March 15, 2018 [Member]
Debt Instrument [Line Items]
Long-term debt	499	499
Debt interest rate	1.40%	1.40%	1.40%
Debt maturity date	15-Mar-18	15-Mar-18	15-Mar-18
7.50% Notes Due February 15, 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	349	349
Debt interest rate	7.50%	7.50%
Debt maturity date	15-Feb-19	15-Feb-19
2.28% Notes Due March 15, 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	1,100	1,100
Debt interest rate	2.28%	2.28%
Debt maturity date	15-Mar-19	15-Mar-19
4.75% Notes Due March 1, 2021 [Member]
Debt Instrument [Line Items]
Long-term debt	599	598
Debt interest rate	4.75%	4.75%
Debt maturity date	1-Mar-21	1-Mar-21
2.70% Notes Due December 15, 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	400	400
Debt interest rate	2.70%	2.70%	2.70%
Debt maturity date	15-Dec-22	15-Dec-22	15-Dec-22
2.85% Notes Due March 15, 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	400	400
Debt interest rate	2.85%	2.85%	2.85%
Debt maturity date	15-Mar-23	15-Mar-23	15-Mar-23
3.80% Notes Due March 15, 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	1,100	1,100
Debt interest rate	3.80%	3.80%
Debt maturity date	15-Mar-24	15-Mar-24
7.65% Debentures Due March 1, 2027 [Member]
Debt Instrument [Line Items]
Long-term debt	175	175
Debt interest rate	7.65%	7.65%
Debt maturity date	1-Mar-27	1-Mar-27
6.00% Notes Due March 1, 2041 [Member]
Debt Instrument [Line Items]
Long-term debt	493	493
Debt interest rate	6.00%	6.00%
Debt maturity date	1-Mar-41	1-Mar-41
4.88% Notes Due March 15, 2044 [Member]
Debt Instrument [Line Items]
Long-term debt	800	800
Debt interest rate	4.88%	4.88%
Debt maturity date	15-Mar-44	15-Mar-44
Other Long Term Debt [Member]
Debt Instrument [Line Items]
Long-term debt	26	27
4.00% Bonds Due October 18, 2016 [Member]
Debt Instrument [Line Items]
Long-term debt	388	507
Debt interest rate	4.00%	4.00%
Debt maturity date	18-Oct-16	18-Oct-16
4.50% Bonds Due April 26, 2017 [Member]
Debt Instrument [Line Items]
Long-term debt	563	737
Debt interest rate	4.50%	4.50%
Debt maturity date	26-Apr-17	26-Apr-17
Promissory Notes [Member]
Debt Instrument [Line Items]
Long-term debt	0	297
Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Long-term debt	$117	$166
London Interbank Offered Rate (LIBOR) [Member] | Floating Rate Notes Due September 10, 2015 [Member]
Debt Instrument [Line Items]
Debt variable interest rate		0.40%

Variable_Interest_Entities_Var

Variable Interest Entities Variable Interest Entities (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014
Variable Interest Entity [Line Items]
VIE consolidated assets	$144,000,000	$160,000,000
VIE consolidated liabilities	51,000,000	75,000,000
Unconsolidated VIE maximum exposure to loss	$1,200,000,000	$1,200,000,000

Pension_Benefits_Narrative_Det

Pension Benefits (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended
	Dec. 31, 1996	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Expected amortization of prior service cost (credit) in 2016		($1,000,000)
Expected amortization of actuarial gain (loss) in 2016		-47,000,000
Prior service (cost) credit		7,000,000
Amortization of Net actuarial loss		-31,000,000
Expected Benefit Payments in 2016		74,000,000
Expected Benefit Payments in 2017		172,000,000
Expected Benefit Payments in 2018		75,000,000
Expected Benefit Payments in 2019		94,000,000
Expected Benefit Payments in 2020		66,000,000
Expected Benefit Payments, 2021 through 2025		333,000,000
Expected contributions in next fiscal year		54,000,000
Discount Rate, Defined Benefit Liability, Change in Basis Points		-40
United States Defined Contribution Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions to PSIP		75.00%
Defined Contribution Plan, PSIP Expense and Other		103,000,000		83,000,000		65,000,000
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Unit Value Of Cash And Cash Equivalents		$1
Norwegian Public Service Pension Fund (SPK) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plans Obligations In Excess Of Plan Asset Shortfall Percent		1.00%
Defined Benefit Plan, Plans Obligations In Excess Of Plan Asset Shortfall Remedy Period		2 years
Pension And Other Postretirement Defined Benefit Plans, Plan Asset Value		39,000,000
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit, Plan Highest Average Pay Months	60 months
Defined Benefit, Plan Years Prior To Freeze Date	15 years
Defined Benefit Plan, Actuarial Losses, Percentage Exceeding Greater Of Projected Benefit Obligation Or Market Value of Assets		10.00%
Prior service (cost) credit		8,000,000		0		-1,000,000
Amortization of Net actuarial loss		-27,000,000		-32,000,000		-27,000,000
Projected benefit obligation		583,000,000	[1]	540,000,000	[1]	580,000,000	[1]
Discount Rates		3.18%		3.58%
United States [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations		50.00%		50.00%
United States [Member] | Fixed Income Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations		45.00%		45.00%
United States [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations		5.00%		5.00%
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost) credit		2,000,000		2,000,000		0
Amortization of Net actuarial loss		-5,000,000		-4,000,000		-4,000,000
Projected benefit obligation		963,000,000	[1]	934,000,000	[1]	156,000,000	[1]
Discount Rates		2.50%		3.92%
Discount Rate, Defined Benefit Liability, Change in Basis Points		-142
Pensjonsordningen for Apoteketaten (POA) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Employer Contributions Percent Exceed Plan Asset		5.00%
Defined Benefit Plan, Contributions by Employer		24,000,000		5,000,000
Multiemployer Plans, Funded Status		65.00%
Multiemployer Plans, Withdrawal Obligation		0
Unfunded plan [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		189,000,000		188,000,000
Unfunded plan [Member] | Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		$222,000,000		$260,000,000
Second Part Of Pay Contribution [Member] | United States Defined Contribution Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Company Match Employee Contributions		50.00%
Employee Contributions		2.00%
First Part Of Pay Contribution [Member] | United States Defined Contribution Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Company Match Employee Contributions		100.00%
Employee Contributions		3.00%
[1]	The benefit obligation is the projected benefit obligation.

Pension_Benefits_Schedule_Of_N

Pension Benefits (Schedule Of Net Periodic Expense For Pension Plans) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost-benefits earned during the year	$1	$4	$4
Interest cost on projected benefit obligation	19	19	21
Expected return on assets	-21	-20	-20
Amortization of unrecognized actuarial loss, prior service costs and net transitional obligation	19	32	28
Curtailment gain	0	0	0
Net periodic expense (income)	18	35	33
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost-benefits earned during the year	16	6	3
Interest cost on projected benefit obligation	34	11	7
Expected return on assets	-30	-12	-8
Amortization of unrecognized actuarial loss, prior service costs and net transitional obligation	3	4	4
Curtailment gain	6	-1	0
Net periodic expense (income)	$29	$8	$6

Pension_Benefits_Schedule_Of_C

Pension Benefits (Schedule Of Changes In Benefit Obligations And Plan Assets) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period	$540	[1]	$580	[1]
Service cost	1		4		4
Interest cost	19		19		21
Actuarial (gain) loss	53		-24
Benefit payments	-30		-30
Amendments	0		-9
Acquisitions	0		0
Foreign exchange impact and other	0		0
Benefit obligation at end of period (1)	583	[1]	540	[1]	580	[1]
Fair value of plan assets at beginning of period	300		290
Actual return on plan assets	16		28
Employer and participant contributions	12		12
Defined Benefit Plan, Benefits Paid, Net of Contribution	-30		-30
Acquisitions	0		0
Foreign exchange impact and other	0		0
Fair value of plan assets at end of period	298		300		290
Funded status at end of period	-285		-240
Current liabilities	-17		-13
Long-term liabilities	-268		-227
Total	-285		-240
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period	934	[1]	156	[1]
Service cost	16		6		3
Interest cost	34		11		7
Actuarial (gain) loss	194		15
Benefit payments	-49		-12
Amendments	-6		0
Acquisitions	0		740
Foreign exchange impact and other	-160		18
Benefit obligation at end of period (1)	963	[1]	934	[1]	156	[1]
Fair value of plan assets at beginning of period	590		135
Actual return on plan assets	88		11
Employer and participant contributions	73		12
Defined Benefit Plan, Benefits Paid, Net of Contribution	-49		-10
Acquisitions	0		426
Foreign exchange impact and other	-90		16
Fair value of plan assets at end of period	612		590		135
Funded status at end of period	-351		-344
Current liabilities	-6		-9
Long-term liabilities	-345		-335
Total	($351)		($344)
[1]	The benefit obligation is the projected benefit obligation.

Pension_Benefits_Schedule_Of_P

Pension Benefits (Schedule Of Projected Benefit Obligation, Accumulated Benefit Obligation And Fair Value Of Plan Assets For Pension Plans) (Details) (USD $)	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
In Millions, unless otherwise specified
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$583	[1]	$540	[1]	$580	[1]
Accumulated benefit obligation	583		540
Pension Plan Assets	298		300		290
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	963	[1]	934	[1]	156	[1]
Accumulated benefit obligation	897		894
Pension Plan Assets	$612		$590		$135
[1]	The benefit obligation is the projected benefit obligation.

Pension_Benefits_Schedule_Of_A

Pension Benefits (Schedule Of Amounts Recognized In Accumulated Other Comprehensive Income) (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014
In Millions, unless otherwise specified
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$175	$71
Prior service cost	-6	0
Total	169	71
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	220	188
Prior service cost	0	-7
Total	$220	$181

Pension_Benefits_Schedule_Of_O

Pension Benefits (Schedule Of Other Changes In Accumulated Other Comprehensive Income) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	($31)
Prior service (cost) credit	7
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	58	-31	59
Prior service credit	0	-8	0
Net actuarial loss	-27	-32	-27
Prior service (cost) credit	8	0	-1
Foreign exchange impact and other	0	-1	0
Total recognized in net periodic benefit cost and other comprehensive loss (income)	39	-72	31
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	117	12	11
Prior service credit	-8	0	0
Net actuarial loss	-5	-4	-4
Prior service (cost) credit	2	2	0
Foreign exchange impact and other	-8	4	-4
Total recognized in net periodic benefit cost and other comprehensive loss (income)	$98	$14	$3

Pension_Benefits_Schedule_Of_W

Pension Benefits (Schedule Of Weighted-Average Assumptions Used to Estimate Net Periodic Pension Expense and Actuarial Present Value of Benefit Obligations) (Details)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension expense, Discount rates	3.74%	3.39%	4.11%
Net periodic pension expense, Rate of increase in compensation	4.00%	4.00%	4.00%
Net periodic pension expense, Expected long-term rate of return on plan assets	7.25%	7.25%	7.25%
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rates	3.18%	3.58%	3.40%
Benefit Obligations Assumptions Rate Increase in Compensation	4.00%	4.00%	4.00%
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension expense, Discount rates	3.85%	3.95%	4.50%
Net periodic pension expense, Rate of increase in compensation	3.11%	2.66%	3.10%
Net periodic pension expense, Expected long-term rate of return on plan assets	5.39%	5.71%	6.13%
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rates	2.50%	3.92%	4.10%
Benefit Obligations Assumptions Rate Increase in Compensation	3.24%	3.27%	3.05%

Pension_Benefits_Schedule_Of_S

Pension Benefits (Schedule Of Sensitivity To Changes In Weighted-Average Discount Rate For Pension Plans) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
One percentage point increase on projected benefit obligation	($41)
One percentage point decrease on projected benefit obligation		48
One percentage point increase on net periodic pension cost	-3
One percentage point decrease on net periodic pension cost		4
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
One percentage point increase on projected benefit obligation	-149
One percentage point decrease on projected benefit obligation		180
One percentage point increase on net periodic pension cost	-2
One percentage point decrease on net periodic pension cost		$5

Pension_Benefits_Summary_Of_Pe

Pension Benefits (Summary Of Pension Plan Assets Using Fair Value Hierarchy By Asset Class) (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014		Mar. 31, 2013
In Millions, unless otherwise specified
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	$298	$300		$290
United States [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	56	8
United States [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	18	19
United States [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	138	132
United States [Member] | Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	14	7
United States [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	14	22
United States [Member] | Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	14	10
United States [Member] | Asset-backed Securities and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	26	22
United States [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	63
United States [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	18	16
United States [Member] | Other Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Other funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets		299
United States [Member] | Receivable [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets		1	[1]
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	55	8
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	18	19
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Asset-backed Securities and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Other Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Other funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 1 [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	73	27
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	1	0
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	138	132
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	14	7
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	14	22
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	14	10
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	26	22
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	63
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Other Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Other funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 2 [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	207	256
United States [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	18	16		14
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	18	16		14
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Other Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Other funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
United States [Member] | Fair Value, Inputs, Level 3 [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	18	16
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	612	590		135
Foreign Pension Plan, Defined Benefit [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	8	7
Foreign Pension Plan, Defined Benefit [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	156	163
Foreign Pension Plan, Defined Benefit [Member] | Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	79	4
Foreign Pension Plan, Defined Benefit [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	13	242
Foreign Pension Plan, Defined Benefit [Member] | Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Asset-backed Securities and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	191	45
Foreign Pension Plan, Defined Benefit [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	26	26
Foreign Pension Plan, Defined Benefit [Member] | Other Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	13	52
Foreign Pension Plan, Defined Benefit [Member] | Other funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	126	51
Foreign Pension Plan, Defined Benefit [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets		590
Foreign Pension Plan, Defined Benefit [Member] | Receivable [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets		0	[1]
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	8	7
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	7	6
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	26	4
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	6
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Asset-backed Securities and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	64	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Other Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	3
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Other funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	7	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	112	26
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	149	157
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	53	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	13	236
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	127	45
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	19
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Other Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	13	49
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Other funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	115	46
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	470	552
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	30	12		5
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	26	7		5
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Other Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	0
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Other funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	4	5
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	$30	$12
[1]	Represents pending trades at MarchB 31, 2014.

Pension_Benefits_Schedule_Of_R

Pension Benefits (Schedule Of Reconciliation Of Level 3 Plan Assets Held) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of period	$300	$290
Acquisitions	0	0
Fair value of plan assets at end of period	298	300
United States [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of period	16	14
Acquisitions	0	0
Purchases, sales and settlements	0	0
Unrealized gain on plan assets still held	2	2
Fair value of plan assets at end of period	18	16
United States [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of period	18	16
United States [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of period	16	14
Acquisitions	0	0
Purchases, sales and settlements	0	0
Unrealized gain on plan assets still held	2	2
Fair value of plan assets at end of period	18	16
United States [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of period	0	0
Acquisitions	0	0
Purchases, sales and settlements	0	0
Unrealized gain on plan assets still held	0	0
Fair value of plan assets at end of period	0	0
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of period	590	135
Acquisitions	0	-426
Fair value of plan assets at end of period	612	590
Foreign Pension Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of period	12	5
Acquisitions	0	6
Purchases, sales and settlements	17	0
Unrealized gain on plan assets still held	1	1
Fair value of plan assets at end of period	30	12
Foreign Pension Plan, Defined Benefit [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of period	26	26
Foreign Pension Plan, Defined Benefit [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of period	7	5
Acquisitions	0	1
Purchases, sales and settlements	18	0
Unrealized gain on plan assets still held	1	1
Fair value of plan assets at end of period	26	7
Foreign Pension Plan, Defined Benefit [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of period	5	0
Acquisitions	0	5
Purchases, sales and settlements	-1	0
Unrealized gain on plan assets still held	0	0
Fair value of plan assets at end of period	$4	$5

Postretirement_Benefits_Narrat

Postretirement Benefits (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	$172
Expected amortization of actuarial loss from stockholders' equity in 2016	-47
Other postretirement plan expected future benefit payments, 2021 through 2025	333
Expected contributions for postretirement benefit plans in 2016	54
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	75
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	94
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	66
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments, Year Two		0
Net actuarial gains (losses) for post retirement plans	-1	8
Net prior service credits for post retirement plans	1	1
Net actuarial gains (loss) for changes in benefit obligations	-9	2	7
Expected amortization of actuarial loss from stockholders' equity in 2016	1
Amortization of actuarial loss from stockholders' equity	4
Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Beginning 2016	10
Other postretirement plan expected future benefit payments, 2021 through 2025	44
Expected contributions for postretirement benefit plans in 2016	10
Weighted-average discount rates used to estimate postretirement welfare benefit expenses	4.07%	3.84%	4.44%
Weighted-average discount rates for actuarial present value of benefit obligations	3.61%	4.08%	3.84%
Actuarial Gain Loss Postretirement Welfare Benefit Plan Amortization Period	3 years
Defined Benefit Plan, Expected Future Benefit Payments, Year Three		0
Defined Benefit Plan, Expected Future Benefit Payments, Year Four		0
Defined Benefit Plan, Expected Future Benefit Payments, Year Five		$0
Prescription Drugs [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate	6.75%	7.00%
Dental [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Plans, Assumptions Used Calculating Postretirement Benefit Obligation	5.00%	5.00%
Pre-65 [Member] | Medical [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Plans, Assumptions Used Calculating Postretirement Benefit Obligation	7.25%	7.50%
Pension and Other Postretirement Benefit Plans, Assumptions Used Calculating Postretirement Benefit Obligation, Age Threshold	pre-65
Post-65 [Member] | Medical [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Plans, Assumptions Used Calculating Postretirement Benefit Obligation	6.75%	7.00%
Pension and Other Postretirement Benefit Plans, Assumptions Used Calculating Postretirement Benefit Obligation, Age Threshold	post-65

Postretirement_Benefits_Schedu

Postretirement Benefits (Schedule Of Net Periodic Expense (Income) For Postretirement Welfare Benefits) (Details) (Other Postretirement Benefit Plan, Defined Benefit [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$1	$2	$2
Interest cost	5	5	6
Amortization of unrecognized actuarial gain and prior service costs	-4	-1	-2
Curtailment gain	0	-2	0
Net periodic expense (income)	$2	$4	$6

Postretirement_Benefits_Schedu1

Postretirement Benefits (Schedule Of Changes In Benefit Obligations For Postretirement Welfare Plans) (Details) (Other Postretirement Benefit Plan, Defined Benefit [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period	$119	$131
Service cost	1	2	2
Interest cost	5	5	6
Actuarial (gain) loss	5	-2
Benefit payments	-12	-15
Defined Benefit Plan, Curtailments	0	-2
Benefit obligation at end of period (1)	$118	$119	$131

Hedging_Activities_Narrative_D

Hedging Activities (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Forward Contracts [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, notional amount	$399	$463
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, notional amount	1,755	1,091
Gain (loss) on derivatives	-189
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, notional amount		$96
Minimum [Member] | Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Foreign currency derivatives, maturity date	31-Mar-16
Minimum [Member] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Foreign currency derivatives, maturity date	1-Apr-15
Maximum [Member] | Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Foreign currency derivatives, maturity date	31-Mar-20
Maximum [Member] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Foreign currency derivatives, maturity date	4-Feb-16

Hedging_Activities_Derivative_1

Hedging Activities Derivative Instruments Fair Value (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014
In Millions, unless otherwise specified
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, gross fair value	$67	$31
Derivative liability, gross fair value	0	0
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, gross fair value	14	4
Derivative liability, gross fair value	0	0
Derivative asset, notional amount	76	64
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, gross fair value	53	27
Derivative liability, gross fair value	0	0
Derivative asset, notional amount	323	399
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, gross fair value	7	2
Derivative liability, gross fair value	79	14
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, gross fair value	7	2
Derivative liability, gross fair value	0	0
Derivative asset, notional amount	493	255
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, gross fair value	0	0
Derivative liability, gross fair value	79	13
Derivative liability, notional amount	1,262	836
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, gross fair value	0	0
Derivative liability, gross fair value	0	1
Derivative liability, notional amount	$0	$96

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2015	Sep. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	$9,700,000,000	$10,300,000,000		$9,700,000,000
Impairment of an equity investment	0	0	191,000,000
Distribution Solutions [Member] | Nadro [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of an equity investment			191,000,000
Equity interest in investee		49.00%	49.00%		49.00%
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	10,400,000,000	10,700,000,000		10,400,000,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Nadro [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of an equity investment			191,000,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Technology Solutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment			36,000,000
Brazil Distribution [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges				241,000,000
Impairment charges, net of tax				235,000,000
Brazil Distribution [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges	241,000,000
Impairment charges, net of tax	235,000,000
International Technology [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges		80,000,000
Impairment charges, net of tax		80,000,000
International Technology [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges		$80,000,000

Fair_Value_Measurements_Fair_V

Fair Value Measurements (Fair Value Measurements, Recurring) (Details) (Fair Value, Measurements, Recurring [Member], USD $)	Mar. 31, 2015		Mar. 31, 2014
In Millions, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	$4,217		$2,865
Money Market Funds (1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	2,880	[1]	2,284	[1]
Time Deposits (2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	94	[2]	12	[2]
Repurchase Agreements (2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	1,243	[2]	569	[2]
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	4,123		2,853
Fair Value, Inputs, Level 1 [Member] | Money Market Funds (1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	2,880	[1]	2,284	[1]
Fair Value, Inputs, Level 1 [Member] | Time Deposits (2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	0	[2]	0	[2]
Fair Value, Inputs, Level 1 [Member] | Repurchase Agreements (2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	1,243	[2]	569	[2]
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	94		12
Fair Value, Inputs, Level 2 [Member] | Money Market Funds (1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	0	[1]	0	[1]
Fair Value, Inputs, Level 2 [Member] | Time Deposits (2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	94	[2]	12	[2]
Fair Value, Inputs, Level 2 [Member] | Repurchase Agreements (2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	0	[2]	0	[2]
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	0		0
Fair Value, Inputs, Level 3 [Member] | Money Market Funds (1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	0	[1]	0	[1]
Fair Value, Inputs, Level 3 [Member] | Time Deposits (2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	0	[2]	0	[2]
Fair Value, Inputs, Level 3 [Member] | Repurchase Agreements (2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value	$0	[2]	$0	[2]
[1]	Gross unrealized gain and losses were not material for the years ended March 31, 2015 and 2014 based on quoted prices of identical investments.
[2]	The carrying amounts of these cash equivalents approximated their estimated fair values because of their short maturities.

Lease_Obligations_Narrative_De

Lease Obligations (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Operating Leased Assets [Line Items]
Minimum sublease rentals, due under future noncancelable subleases	$46
Rent expense	$440	$298	$232
Renewal option increments for leases (years)	5 years
Building [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Lease term (years)	1 year
Building [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Lease term (years)	12 years
Equipment [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Lease term (years)	1 year
Equipment [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Lease term (years)	5 years

Lease_Obligations_Schedule_Of_

Lease Obligations (Schedule Of Future Minimum Rental Payments For Operating Leases) (Details) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Leases, Operating [Abstract]
2016	$316
2017	271
2018	219
2019	170
2020	140
Thereafter	650
Total minimum lease payments (1)	$1,766	[1]
[1]	Minimum lease payments have not been reduced by minimum sublease rentals of $46 million due under future noncancelable subleases.

Financial_Guarantees_and_Warra1

Financial Guarantees and Warranties (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	$1
Guarantee obligations, expiring in 2016	137
Guarantee obligations, expiring in 2017	42
Guarantee obligations, expiring in 2018	16
Guarantee obligations, expiring in 2019	21
Guarantee obligations, expiring in 2020	25
Guarantee obligations, expiring after 2020	127
Guarantee Obligations Inventory Repurchase Guarantees [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure	185
Guarantee Obligations Inventory Repurchase Guarantees [Member] | Minimum [Member]
Guarantor Obligations [Line Items]
Number of years for which agreements or guarantees extend	1
Guarantee Obligations Inventory Repurchase Guarantees [Member] | Maximum [Member]
Guarantor Obligations [Line Items]
Number of years for which agreements or guarantees extend	2
Guarantee Obligations Customers Debt [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure	183
Guarantee Obligations Customers Debt [Member] | Minimum [Member]
Guarantor Obligations [Line Items]
Number of years for which agreements or guarantees extend	1
Guarantee Obligations Customers Debt [Member] | Maximum [Member]
Guarantor Obligations [Line Items]
Number of years for which agreements or guarantees extend	15
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Letters of credit outstanding	142
Commitment to investee building and equipment construction [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure	$16

Other_Commitments_and_Continge1

Other Commitments and Contingent Liabilities (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2015
Loss Contingencies [Line Items]
Claims and litigation charges	$150	$68	$72
Anti-Kickback Claim [Member]
Loss Contingencies [Line Items]
Loss Contingency Number of States Filed On Behalf Of	21
Loss Contingency Number of Relators	2
Loss Contingency Number of Additional Defendants	5
Controlled Substance Investigation [Member]
Loss Contingencies [Line Items]
Claims and litigation charges	150			150
Claims and litigation charges, net of tax	150
Environmental Litigation [Member]
Loss Contingencies [Line Items]
Chemical conditions sites, number	6
Remediation costs	7			7
Hazardous substance sites, number	14
Estimated environmental assessment and cleanup costs	70
Estimated loss	22			22
Environmental Litigation [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Site Contingency, Time Frame of Disbursements	4/1/15
Environmental Litigation [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Site Contingency, Time Frame of Disbursements	3/31/35
Average Wholesale Price Litigation [Member]
Loss Contingencies [Line Items]
Claims and litigation charges	$0	$68	$72

Other_Commitments_and_Continge2

Other Commitments and Contingent Liabilities (Litigation Reserve and Expense) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Loss Contingencies [Line Items]
Claims and litigation charges	$150	$68	$72
Payments for Legal Settlements	0	105	483
Average Wholesale Price Litigation [Member]
Loss Contingencies [Line Items]
Claims and litigation charges	0	68	72
Payments for Legal Settlements	0	105	483
Estimated Litigation Liability		$42

Stockholders_Equity_Narrative_

Stockholders' Equity (Narrative) (Details) (USD $)

0 Months Ended

12 Months Ended

In Millions, except Per Share data, unless otherwise specified

Jul. 26, 2013

Jul. 25, 2013

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2013

Apr. 30, 2015

Jan. 31, 2013

Apr. 30, 2012

Sep. 30, 2013

Dividends Payable [Line Items]

Cash dividends declared per common share

$0.24

$0.20

$0.96

$0.92

$0.80

Stock repurchase plans approved, shares

$500

$500

[1]

$700

[1]

Treasury stock retired

2

Treasury stock retired, acquired amount

217

Treasury stock retired, amount

195

OCI foreign currency translation gains (losses) net of tax, NCI portion

-267

21

Net foreign currency gains (losses), reclassified from AOCI

$10

[2]

($44)

[2]

$0

[2]

Nadro [Member] | Distribution Solutions [Member]

Dividends Payable [Line Items]

Equity interest in investee

49.00%

49.00%

49.00%

[1]

This table does not include shares tendered to satisfy the exercise price in connection with cashless exercises of employee stock options or shares tendered to satisfy tax withholding obligations in connection with employee equity awards.

[2]

2014 includes net foreign currency translation losses of $44 million reclassified from accumulated other comprehensive income to other income (loss), net, within our consolidated statement of operations due to the sale of our 49% equity interest in Nadro. Such losses were previously considered in our impairment evaluation of the investment when we committed to a plan to sell the investment during the fourth quarter of 2013 and, accordingly, did not impact earnings in 2014.

Stockholders_Equity_Shares_Rep

Stockholders' Equity (Shares Repurchases) (Details) (USD $)

12 Months Ended

In Millions, except Per Share data, unless otherwise specified

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2013

Apr. 30, 2015

Jan. 31, 2013

Apr. 30, 2012

Mar. 31, 2012

Stockholders' Equity Note [Abstract]

Approximate dollar value of shares that may yet to be purchased under the programs

$0

[1]

$340

[1]

$340

[1]

$299

[1]

Stock repurchase plans approved, shares

500

500

[1]

700

[1]

Repurchase of common stock

($340)

[1]

$0

($1,159)

[1]

Number of shares repurchased

1.5

[1],[2],[3]

0

13

[1],[2],[3]

Average price paid per share

$226.55

[1]

$0

$100.82

[1]

[1]

This table does not include shares tendered to satisfy the exercise price in connection with cashless exercises of employee stock options or shares tendered to satisfy tax withholding obligations in connection with employee equity awards.

[2]

All of the shares purchased were part of the publicly announced programs.

[3]

The number of shares purchased reflects rounding adjustments.

Stockholders_Equity_Other_Comp

Stockholders' Equity (Other Comprehensive Income (Loss), Net of Tax) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Stockholders' Equity Note [Abstract]
Foreign currency translation adjustments arising during period, net of income tax expense (benefit) of nil, nil and ($2) (1)	($1,845)	[1]	$9	[1]	($52)	[1]
Reclassified to income statement, net of income tax expense of nil, $24 and nil (2)	-10	[2]	44	[2]	0	[2]
Foreign currency translation adjustments, net of income tax expense (benefit) of $24, ($2) and $2	-1,855		53		-52
Unrealized losses on cash flow hedges arising during period, net of income tax benefit of nil, nil and nil	-13		-6		0
Reclassified to income statement, net of income tax expense of nil, nil and nil	3		0		0
Unrealized losses on cash flow hedges, net of tax	-10		-6		0
Net actuarial gain (loss) and prior service credit (cost) arising during period, net of income tax (benefit) of ($66), $16 and ($22)	-140		17		-40
Amortization of actuarial loss, prior service cost and transition obligation, net of income tax expense of $6, $12 and $12 (3)	11	[3]	22	[3]	18	[3]
Foreign currency translation adjustments and other, net of income tax expense of nil, nil and nil	4		-4		4
Reclassified to income statement, net of income tax expense of nil, $1 and nil	1		1		0
Retirement related benefit plans, net of income tax expense (benefit) of ($10), ($10) and ($9)	-124		36		-18
Other Comprehensive Income (Loss), Net of Tax	($1,989)		$83		($70)
[1]	2015 includes net foreign currency translation losses of $267 million and 2014 includes net foreign currency translations gains of $21 million attributable to noncontrolling and redeemable noncontrolling interests.
[2]	2014 includes net foreign currency translation losses of $44 million reclassified from accumulated other comprehensive income to other income (loss), net, within our consolidated statement of operations due to the sale of our 49% equity interest in Nadro. Such losses were previously considered in our impairment evaluation of the investment when we committed to a plan to sell the investment during the fourth quarter of 2013 and, accordingly, did not impact earnings in 2014.
[3]	Pre-tax amount was reclassified into cost of sales and operating expenses in the consolidated statements of operations. The related tax expense was reclassified into income tax expense in the consolidated statements of operations.

Stockholders_Equity_Changes_in

Stockholders' Equity (Changes in Accumulated Other Comprehensive Income by Component) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance	($3)
Other Comprehensive Income (Loss), Net of Tax	-1,989	83	-70
Ending balance	-1,713	-3
Parent Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance	-3	-65
Other comprehensive income (loss) before reclassifications	-1,994	38
Amounts reclassified to earnings and other	5	45
Other comprehensive income (loss) including portion attributable to NCI, net of tax	-1,989	83
Other comprehensive income (loss) attributable to NCI, net of tax	-279	21
Other Comprehensive Income (Loss), Net of Tax	-1,710	62
Ending balance	-1,713	-3
Accumulated Translation Adjustment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance	168	136
Other comprehensive income (loss) before reclassifications	-1,845	9
Amounts reclassified to earnings and other	-10	44
Other comprehensive income (loss) including portion attributable to NCI, net of tax	-1,855	53
Other comprehensive income (loss) attributable to NCI, net of tax	-267	21
Other Comprehensive Income (Loss), Net of Tax	-1,588	32
Ending balance	-1,420	168
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance	-11	-5
Other comprehensive income (loss) before reclassifications	-13	-6
Amounts reclassified to earnings and other	3	0
Other comprehensive income (loss) including portion attributable to NCI, net of tax	-10	-6
Other comprehensive income (loss) attributable to NCI, net of tax	0	0
Other Comprehensive Income (Loss), Net of Tax	-10	-6
Ending balance	-21	-11
Accumulated Defined Benefit Plans Adjustment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance	-160	-196
Other comprehensive income (loss) before reclassifications	-136	35
Amounts reclassified to earnings and other	12	1
Other comprehensive income (loss) including portion attributable to NCI, net of tax	-124	36
Other comprehensive income (loss) attributable to NCI, net of tax	-12	0
Other Comprehensive Income (Loss), Net of Tax	-112	36
Ending balance	($272)	($160)

Stockholders_Equity_Other_Comp1

Stockholders' Equity (Other Comprehensive Income (Loss), Tax (Phantom)(Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Stockholders' Equity Note [Abstract]
Foreign currency translation adjustments arising during period, net of income tax expense (benefit) of nil, nil and ($2)	$0	$0	($2)
Reclassified to income statement, income tax expense of nil, $24 and nil	0	24	0
Unrealized losses on cash flow hedges arising during period, tax benefit of nil, nil and nil	0	0	0
Reclassification to income statement, net of income tax expense of nil, nil and nil	0	0	0
Net actuarial gain (loss) arising during period, net of income tax (benefit) of ($66), $16 and ($22)	-66	16	-22
Amortization of actuarial loss, prior service cost and transition obligation, net of income tax (benefit) of $6, $12 and $12	6	12	12
Foreign currency translation adjustments, net of income tax expense of nil, nil and nil	0	0	0
Reclassified to income statement, income tax expense of nil, $1 and nil	$0	$1	$0

Related_Party_Balances_and_Tra1

Related Party Balances and Transactions (Narrative) (Details) (Investee [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Investee [Member]
Related Party Transaction [Line Items]
Revenue from related parties	$114
Accounts receivable, related parties, current	$9

Segments_of_Business_Narrative

Segments of Business (Narrative) (Details) (Distribution Solutions [Member])	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013
Segment Reporting Information [Line Items]
Percentage of revenue derived from services	less than 2%	less than 2%	less than 2%
Nadro [Member]
Segment Reporting Information [Line Items]
Equity interest in investee		49.00%	49.00%	49.00%

Segments_of_Business_Schedule_

Segments of Business (Schedule Of Segment Information) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$44,925	$46,484	$44,160	$43,476	$37,832	$34,336	$32,985	$32,239	$179,045	[1]	$137,392	[1]	$122,196	[1]
Operating profit									2,968		2,439		2,347
Interest Expense									-374		-300		-240
Income From Continuing Operations Before Income Taxes									2,657		2,171		1,950
Depreciation and amortization									1,017	[2]	735	[2]	581	[2]
Expenditures for long-lived assets									376	[3]	278	[3]	241	[3]
United States [Member]
Segment Reporting Information [Line Items]
Revenues									142,810	[1]	122,426	[1]	112,102	[1]
Foreign [Member]
Segment Reporting Information [Line Items]
Revenues									36,235	[1]	14,966	[1]	10,094	[1]
North America Distribution And Services [Member]
Segment Reporting Information [Line Items]
Revenues									143,711	[4]	123,929	[4]	115,443	[4]
International Distribution and Services [Member]
Segment Reporting Information [Line Items]
Revenues									26,358	[4]	4,485	[4]	0	[4]
Medical Surgical Distribution And Services [Member]
Segment Reporting Information [Line Items]
Revenues									5,907	[4]	5,648	[4]	3,603	[4]
Distribution Solutions [Member]
Segment Reporting Information [Line Items]
Revenues									175,976	[4]	134,062	[4]	119,046	[4]
Operating profit									3,047		2,472		2,195
Depreciation and amortization									750	[2]	446	[2]	267	[2]
Expenditures for long-lived assets									301	[3]	179	[3]	163	[3]
Technology Solutions [Member]
Segment Reporting Information [Line Items]
Revenues									3,069		3,330		3,150
Operating profit									438		448		330
Depreciation and amortization									156	[2]	169	[2]	194	[2]
Expenditures for long-lived assets									27	[3]	47	[3]	37	[3]
Corporate [Member]
Segment Reporting Information [Line Items]
Operating profit									-454		-449		-335
Depreciation and amortization									111	[2]	120	[2]	120	[2]
Expenditures for long-lived assets									48	[3]	52	[3]	41	[3]
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating profit									$3,485		$2,920		$2,525
[1]	Net revenues were attributed to geographic areas based on the customersb shipment locations.
[2]	Amounts primarily include amortization of acquired intangible assets purchased in connection with acquisitions, capitalized software held for sale and capitalized software for internal use.
[3]	Long-lived assets consist of property, plant and equipment.
[4]	Revenues derived from services represent less than 2% of this segmentbs total revenues.

Segments_of_Business_Segment_A

Segments of Business (Segment Assets and Property, Plant and Equipment, Net by Geographica Ares) (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
In Millions, unless otherwise specified
Segment Reporting Information [Line Items]
Assets	$53,870	$51,759
Cash and cash equivalents	5,341	4,193	2,456	3,149
Property, plant and equipment, net	2,045	2,196
United States [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,273	1,246
Foreign [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	772	950
Distribution Solutions [Member]
Segment Reporting Information [Line Items]
Assets	43,982	42,496
Technology Solutions [Member]
Segment Reporting Information [Line Items]
Assets	3,281	3,573
Operating Segments [Member]
Segment Reporting Information [Line Items]
Assets	47,263	46,069
Corporate [Member]
Segment Reporting Information [Line Items]
Other	$1,266	$1,497

Quarterly_Financial_Informatio2

Quarterly Financial Information (Unaudited) (Narrrative) (Details) (USD $)	12 Months Ended			3 Months Ended							9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2014
Quarterly Financial Information [Line Items]
LIFO expense	$337	$311	$13
Claims and litigation charges	150	68	72
Income tax benefit (expense) discrete items	33	-94	29
Distribution Solutions [Member]
Quarterly Financial Information [Line Items]
LIFO expense				50	95	94	98	125	142	44
Inventory fair value step-up reversal								40
Inventory fair value step-up reversal, after-tax								21
Brazil Distribution [Member]
Quarterly Financial Information [Line Items]
Impairment charges, net of tax				235
International Technology [Member]
Quarterly Financial Information [Line Items]
Impairment charges, net of tax		80
Goodwill and intangible asset impairment									80
Canada Revenue Agency Assessments [Member]
Quarterly Financial Information [Line Items]
Income tax benefit (expense) discrete items		122							122
Celesio [Member]
Quarterly Financial Information [Line Items]
Guaranteed dividend amount				12							50
Controlled Substance Investigation [Member]
Quarterly Financial Information [Line Items]
Claims and litigation charges	$150			$150

Quarterly_Financial_Informatio3

Quarterly Financial Information (Unaudited) (Schedule Of Quarterly Financial Information) (Details) (USD $)	3 Months Ended																12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Quarterly Financial Information [Line Items]
Revenues	$44,925		$46,484		$44,160		$43,476		$37,832		$34,336		$32,985		$32,239		$179,045	[1]	$137,392	[1]	$122,196	[1]
Gross profit	2,917	[2]	2,898	[2]	2,864	[2]	2,732	[2]	2,551	[3]	1,850	[3]	2,021	[3]	1,930		11,411		8,352		6,881
Income from continuing operations	411	[2],[4]	521	[2]	491	[2]	419	[2]	399	[3],[5]	164	[3],[5]	423	[3]	428	[3]	1,842		1,414		1,363
Income (Loss) from Discontinued Operations, Net of Tax	-267	[6]	-10		-14		-8		-34		-99	[7]	-19		-4		-299		-156		-25
Net Income	144		511		477		411		365		65		404		424		1,543		1,258		1,338
Net loss attributable to noncontrolling interests	-12	[8]	-39	[8]	-8	[8]	-8	[8]	5	[9]	0	[9]	0	[9]	0	[9]	-67		5		0
Net Income Attributable to McKesson	$132		$472		$469		$403		$370		$65		$404		$424		$1,476		$1,263		$1,338
Earnings (Loss) Per Common Share Attributable to McKesson
Diluted	$0.56	[10]	$2	[10]	$1.99	[10]	$1.72	[10]	$1.58	[10]	$0.28	[10]	$1.74	[10]	$1.83	[10]	$6.27	[10]	$5.41	[10]	$5.59	[10]
Continuing operations	$1.69	[10]	$2.04	[10]	$2.05	[10]	$1.76	[10]	$1.72	[10]	$0.70	[10]	$1.82	[10]	$1.84	[10]	$7.54	[10]	$6.08	[10]	$5.69	[10]
Discontinued operations	($1.13)	[10]	($0.04)	[10]	($0.06)	[10]	($0.04)	[10]	($0.14)	[10]	($0.42)	[10]	($0.08)	[10]	($0.01)	[10]	($1.27)	[10]	($0.67)	[10]	($0.10)	[10]
Basic	$0.57	[10]	$2.03	[10]	$2.02	[10]	$1.75	[10]	$1.61	[10]	$0.28	[10]	$1.76	[10]	$1.86	[10]	$6.37	[10]	$5.51	[10]	$5.71	[10]
Continuing operations	$1.72	[10]	$2.07	[10]	$2.08	[10]	$1.79	[10]	$1.76	[10]	$0.71	[10]	$1.85	[10]	$1.88	[10]	$7.66	[10]	$6.19	[10]	$5.81	[10]
Discontinued operations	($1.15)	[10]	($0.04)	[10]	($0.06)	[10]	($0.04)	[10]	($0.15)	[10]	($0.43)	[10]	($0.09)	[10]	($0.02)	[10]	($1.29)	[10]	($0.68)	[10]	($0.10)	[10]
[1]	Net revenues were attributed to geographic areas based on the customersb shipment locations.
[2]	Financial results for the first, second, third and fourth quarters of 2015 include pre-tax charges in our Distribution Solutions segment related to our last-in-first-out (bLIFOb) method of accounting for inventories of $98 million, $94 million, $95 million and $50 million, which were recorded in cost of sales.
[3]	Financial results for the second, third and fourth quarters of 2014 include pre-tax charges in our Distribution Solutions segment related to our LIFO method of accounting for inventories of $44 million, $142 million and $125 million, which were recorded in cost of sales. The fourth quarter of 2014 also includes a $40 million pre-tax charge to cost of sales within our Distribution Solutions segment representing the reversal of a step-up to fair value of Celesiobs inventory at the date of acquisition. Our after-tax portion of this charge from continuing operations (after allocation to noncontrolling interests) was $21 million.
[4]	Fourth quarter of 2015 includes a non-cash after-tax charge of $150 million related to the settlement of controlled substance distribution claims.
[5]	Financial results for the third quarter of 2014 include an income tax charge of $122 million relating to our litigation with the Canadian Revenue Agency.
[6]	Fourth quarter of 2015 includes $235 million non-cash after-tax impairment charges related to our Brazilian pharmaceutical distribution business.
[7]	Financial results for the third quarter of 2014 include an $80 million after-tax impairment charge related to our International Technology Business, which was sold in part during the second quarter of 2015.
[8]	Primarily reflects the guaranteed dividends of $50 million for the first nine months of 2015 and the recurring compensation of $12 million for the fourth quarter of 2015. McKesson is obligated to pay these amounts to the noncontrolling shareholders of Celesio under the Domination Agreement which became effective in December 2014.
[9]	Primarily represents the noncontrolling shareholdersb portion of net loss from Celesio.
[10]	Certain computations may reflect rounding adjustments.

Supplementary_Consolidated_Fin1

Supplementary Consolidated Financial Statement Schedule Valuation And Qualifying Accounts (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$134	[1]	$136	[1]	$125
Charged to Costs and Expense	75		36		32
Charged to Other Accounts	0	[2]	-1	[2]	17	[2]
Deductions From Allowance Accounts	-35	[3]	-37	[3]	-38	[3]
Balance at End of Year	174	[1]	134	[1]	136	[1]
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	112	[1]	121	[1]	111
Charged to Costs and Expense	67		36		28
Charged to Other Accounts	0	[2]	-11	[2]	16	[2]
Deductions From Allowance Accounts	-38	[3]	-34	[3]	-34	[3]
Balance at End of Year	141	[1]	112	[1]	121	[1]
Other Allowances [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	22	[1]	15	[1]	14
Charged to Costs and Expense	8		0		4
Charged to Other Accounts	0	[2]	10	[2]	1	[2]
Deductions From Allowance Accounts	3	[3]	-3	[3]	-4	[3]
Balance at End of Year	33	[1]	22	[1]	15	[1]
Written Off [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions From Allowance Accounts	-34		-39		-38
Credited To Other Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions From Allowance Accounts	-1		2		0
Amounts Shown As Deductions From Current And Non-Current Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at End of Year	$174		$134		$136
[1]	Amounts shown as deductions from current and non - current receivables [$0], $136, $125.
[2]	Primarily represents reclassifications from other balance sheet accounts.
[3]	Deductions:Written off - [($0)], ($38), ($44)Credited to other accounts - [($0)], ($0), ($6)Total - [($0)], ($38), ($50)