CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (80)	$ 365
Other Comprehensive Income (Loss), Net of Tax
Foreign currency translation adjustments arising during the period	(129)	312
Unrealized gains on cash flow hedges arising during the period	0	14
Retirement-related benefit plans	8	(5)
Other Comprehensive Income (Loss), Net of Tax	(121)	321
Comprehensive Income (Loss)	(201)	686
Comprehensive Income Attributable to Noncontrolling Interests	(21)	(172)
Comprehensive Income (Loss) Attributable to McKesson Corporation	$ (222)	$ 514

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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