Fair Value of Financial Instruments	3 Months Ended
Fair Value of Financial Instruments	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The recorded amounts of the Company’s cash and cash equivalents, accounts receivable, and accounts payable as of December 31, 2017 and September 30, 2017 approximate fair value based upon the relatively short-term nature of these financial instruments. Within Cash and Cash Equivalents, the Company had no investments in money market accounts as of December 31, 2017 and had $800.0 million of investments in money market accounts as of September 30, 2017. The fair value of the money market accounts was determined based upon unadjusted quoted prices in active markets for identical assets, otherwise known as Level 1 inputs. The recorded amount of long-term debt (see Note 5) and the corresponding fair value as of December 31, 2017 were $4,266.8 million and $4,334.9 million, respectively. The recorded amount of long-term debt and the corresponding fair value as of September 30, 2017 were $3,429.9 million and $3,522.5 million, respectively. The fair value of long-term debt was determined based upon inputs other than quoted prices, otherwise known as Level 2 inputs.

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.