Condensed Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net Income	$ 511us-gaap_ProfitLoss	$ 65us-gaap_ProfitLoss	$ 1,399us-gaap_ProfitLoss	$ 893us-gaap_ProfitLoss
Other Comprehensive Income (Loss), Net of Tax
Foreign currency translation adjustments arising during period	(416)	(55)	(995)	(16)
Unrealized losses on cash flow hedges arising during period	1	(1)	(1)	(2)
Retirement-related benefit plans	(16)	4	(8)	15
Other comprehensive income (loss), net of tax	(431)	(52)	(1,004)	(3)
Comprehensive Income (Loss)	80	13	395	890
Comprehensive Loss Attributable to Noncontrolling Interests	13	0	148	0
Comprehensive Income (Loss) Attributable to McKesson	$ 93us-gaap_ComprehensiveIncomeNetOfTax	$ 13us-gaap_ComprehensiveIncomeNetOfTax	$ 543us-gaap_ComprehensiveIncomeNetOfTax	$ 890us-gaap_ComprehensiveIncomeNetOfTax

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 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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