Discontinued Operation (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	3 Months Ended
Dec. 31, 2010	Sep. 30, 2010 Technology Solutions [Member]	Sep. 30, 2010 McKesson Asia Pacific Pty Limited [Member]
Discontinued Operations [Line Items]
Net sales proceeds	$ 109	$ 109
Pre-tax gain from divestiture		95
Discontinued operation - gain on sale, net of tax	72	72
Utilization of capital loss carry-forwards, previously recorded as valuation allowance			$ 15

Pretax gain (loss), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group.

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Gain (loss) after tax expense or benefit, not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group.

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- Definition

The amount of the change in the period in the valuation allowance for a specified deferred tax asset.

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