Financial Instruments and Fair Value Measurements	12 Months Ended
Financial Instruments and Fair Value Measurements	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Financial Instruments and Fair Value Measurements	Financial Instruments and Fair Value Measurements The Company’s institutional money market accounts permit daily redemption and the fair values of these investments are based upon the quoted prices in active markets provided by the holding financial institutions, which are considered Level 1 inputs in the fair value hierarchy. The fair values of these accounts were $228 million and $2.026 billion at September 30, 2018 and 2017, respectively. The Company’s remaining cash and equivalents, excluding restricted cash, were $913 million and $12.153 billion at September 30, 2018 and 2017, respectively. Short-term investments are held to their maturities and are carried at cost, which approximates fair value. The cash equivalents consist of liquid investments with a maturity of three months or less and the short-term investments consist of instruments with maturities greater than three months and less than one year. Long-term debt is recorded at amortized cost. The fair value of long-term debt is measured based upon quoted prices in active markets for similar instruments, which are considered Level 2 inputs in the fair value hierarchy. The fair value of long-term debt was $18.8 billion and $19.2 billion at September 30, 2018 and 2017, respectively. The fair value of the current portion of long-term debt was $1.893 billion and $206 million at September 30, 2018 and 2017, respectively. All other instruments measured by the Company at fair value, including derivatives and contingent consideration liabilities, are immaterial to the Company's consolidated balance sheets. Nonrecurring Fair Value Measurements In fiscal year 2018, the Company recorded charges of $58 million to write down the value of fixed assets, primarily in the Diabetes Care unit, as well as charges of $81 million to write down the carrying value of certain intangible and other assets in the Biosciences unit. In fiscal year 2016, the Company recorded a charge to Acquisitions and other restructurings of $214 million to impair capitalized internal-use software assets held for sale as a result of the Company's transition of certain elements of its information technology infrastructure to an outsourced model. Also in fiscal year 2016, the Company recorded losses of $81 million on the held for sale assets of certain non-core businesses. The amounts recognized in 2018 and 2016 were recorded to adjust the carrying amount of assets to the assets' fair values, which were estimated, based upon a market participant's perspective, using either Level 2 inputs, including quoted prices for similar assets, or Level 3 inputs, including values estimated using the income approach. Concentration of Credit Risk The Company maintains cash deposits in excess of government-provided insurance limits. Such cash deposits are exposed to loss in the event of nonperformance by financial institutions. Substantially all of the Company’s trade receivables are due from public and private entities involved in the healthcare industry. Due to the large size and diversity of the Company’s customer base, concentrations of credit risk with respect to trade receivables are limited. The Company does not normally require collateral. The Company is exposed to credit loss in the event of nonperformance by financial institutions with which it conducts business. However, this loss is limited to the amounts, if any, by which the obligations of the counterparty to the financial instrument contract exceed the obligations of the Company. The Company also minimizes exposure to credit risk by dealing with a diversified group of major financial institutions. The Company continually evaluates its accounts receivables for potential collection risks particularly those resulting from sales to government-owned or government-supported healthcare facilities in certain countries as payment may be dependent upon the financial stability and creditworthiness of those countries’ national economies. The Company continually evaluates all governmental receivables for potential collection risks associated with the availability of government funding and reimbursement practices. The Company believes the current reserves related to all governmental receivables are adequate and that this concentration of credit risk will not have a material adverse impact on its financial position or liquidity.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.