Income Taxes	6 Months Ended
Income Taxes	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes During the three months ended September 30, 2020 and 2019, the Company recorded income tax expense of $28 million and an income tax benefit of $294 million, respectively, related to continuing operations. During the six months ended September 30, 2020 and 2019, the Company recorded income tax expense of $178 million and an income tax benefit of $158 million, respectively, related to continuing operations. The Company’s reported income tax rates were expense of 4.3% and benefit of 30.3% for the three months ended September 30, 2020 and 2019, respectively and expense of 13.7% and benefit of 45.0% for the six months ended September 30, 2020 and 2019, respectively. Fluctuations in the Company’s reported income tax rates are primarily due to changes within the mix of earnings between various taxing jurisdictions and discrete items recognized in the quarters, primarily due to the impact of an intercompany sale of intellectual property during the three months ended September 30, 2020. During the second quarter of 2021, the Company sold intellectual property between wholly-owned legal entities within McKesson that are based in different tax jurisdictions. The transferor entity recognized a gain on the sale of assets which was not subject to income tax in its local jurisdiction; such gain was eliminated upon consolidation. The acquiring entity of the intellectual property is entitled to amortize the purchase price of the assets for tax purposes. In accordance with ASU 2016-16, “Intra-Entity Transfers of Assets Other Than Inventory,” a discrete tax benefit of $105 million, which reduced the Company’s reported income tax rates by 16.0 percentage points and 8.1 percentage points for the three and six months ended September 30, 2020, respectively, was recognized with a corresponding increase to a deferred tax asset for the temporary difference arising from the buyer’s excess tax basis. As of September 30, 2020, the Company had $1 billion of unrecognized tax benefits, of which $882 million would reduce income tax expense and the effective tax rate if recognized. During the next twelve months, it is reasonably possible that the Company’s unrecognized tax benefits may decrease by as much as $105 million due to settlements of tax examinations and statute of limitations expirations in the U.S. federal and state jurisdictions and in foreign jurisdictions. However, this amount may change as the Company continues to have ongoing negotiations with various taxing authorities throughout the year. The Company files income tax returns in the U.S. federal jurisdiction, various U.S. state jurisdictions, and various foreign jurisdictions. The Internal Revenue Service (“IRS”) is currently examining the Company’s U.S. corporation income tax returns for 2016 through 2019. The Company is generally subject to audit by taxing authorities in various U.S. states and in foreign jurisdictions for fiscal years 2013 through the current fiscal year.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.