Long-term Debt and Finance Lease Obligations, Lines of Credit, and Fair Value Disclosure	6 Months Ended
	Oct. 31, 2020
Long-Term Debt and Fair Value Disclosure [Abstract]
Long-term Debt and Finance Lease Obligations, Lines of Credit, and Fair Value Disclosure	Long-Term Debt and Finance Lease Obligations, Lines of Credit, and Fair Value Disclosure The fair value of the Company’s long-term debt (including current maturities) is estimated based on the current rates offered to the Company for debt of the same or similar issuances. The fair value of the Company’s long-term debt was approximately $1,415,000 and $1,341,000 at October 31, 2020 and April 30, 2020, respectively. The Company has a credit agreement that provides for a $300 million unsecured revolving credit facility which includes a $30 million sublimit for letters of credit and a $30 million sublimit for swingline loans (the "Credit Facility"). The Credit Facility contains an expansion option permitting the Company to request an increase of the Credit Facility from time to time up to an aggregate additional $150 million from the lenders or other financial institutions acceptable to the Company and the Administrative Agent, upon the satisfaction of certain conditions, including the consent of the lenders whose commitments would increase. The maturity date is January 11, 2024. Amounts borrowed under the Credit Facility bear interest at variable rates based upon, at the Company's option, either (a) LIBOR plus an applicable margin or (b) an alternate base rate. The Credit Facility also carries a facility fee between 0.2% and 0.4% per annum based on the Company's consolidated leverage ratio as defined in the credit agreement. The Company had $0 outstanding at October 31, 2020 and $120,000 outstanding at April 30, 2020. The Company also has an unsecured revolving line of credit of $25,000 (the "Bank Line"), under which there was $0 outstanding at October 31, 2020 and April 30, 2020. On June 30, 2020, the Company entered into a note purchase agreement with respect to the issuance of $650,000 aggregate principal amount of senior notes, consisting of: (i) $325,000 aggregate principal amount of 2.85% Senior Notes, Series G (the “Series G Notes”); and (ii) $325,000 aggregate principal amount of 2.96% Senior Notes, Series H (the “Series H Notes”) (collectively, the “Notes”). The Notes were issued on August 7, 2020. The Series G Notes will bear interest at the rate of 2.85% per annum, payable semi-annually on February 7 and August 7 of each year, and will mature on August 7, 2030. The Series H Notes will bear interest at the rate of 2.96% per annum, payable semi-annually on February 7 and August 7 of each year, and will mature on August 6, 2032. The Company used a portion of the proceeds of the Notes to pay off the $569,000 5.22% senior notes that matured on August 9, 2020.

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.