Long-Term Debt (Details Textuals) - USD ($) $ in Thousands						4 Months Ended	12 Months Ended			15 Months Ended	48 Months Ended
	Jul. 31, 2020	Jul. 31, 2020	Jul. 21, 2020	Jul. 21, 2016	Mar. 15, 2016	Jul. 20, 2016	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018	Mar. 14, 2016	Jul. 20, 2020	Dec. 03, 2014
Line of Credit Facility [Line Items]
Total Consolidated Net Leverage Ratio							(3.00%)
Minimum Liquidity	$ 1,500,000	$ 1,500,000					$ 1,500,000
Applicable interest rate added to reference rate in order to compute variable interest rate							1.50%
Debt instrument costs							$ 2,814	$ 0	$ 0
Scenario 1 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Covenant Terms 1							325.00%
Note Agreement, Covenant Terms							325.00%
Scenario 2 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Covenant Terms 1							350.00%
Note Agreement, Covenant Terms							350.00%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument costs			$ 2,800
Revolving Credit Facility | Line of Credit | Minimum
Line of Credit Facility [Line Items]
Commitment fee rate range						0.15%
Revolving Credit Facility | Line of Credit | Maximum
Line of Credit Facility [Line Items]
Commitment fee rate range						0.30%
Credit Agreement | Term Loan Facility
Line of Credit Facility [Line Items]
Maturity date						Dec. 03, 2019
Note Purchase Agreement | Senior Notes
Line of Credit Facility [Line Items]
Senior notes												$ 400,000
4.07% Senior Notes, Series A | Senior Notes
Line of Credit Facility [Line Items]
Senior notes												$ 100,000
Stated interest rate												4.07%
4.19% Senior Notes, Series B | Senior Notes
Line of Credit Facility [Line Items]
Senior notes												$ 100,000
Stated interest rate												4.19%
4.25% Senior Notes, Series C | Senior Notes
Line of Credit Facility [Line Items]
Senior notes												$ 100,000
Stated interest rate												4.25%
4.35% Senior Notes, Series D | Senior Notes
Line of Credit Facility [Line Items]
Senior notes												$ 100,000
Stated interest rate												4.35%
Federal Funds Rate
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate							0.50%
Eurodollar [Member]
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate							1.00%
Eurodollar [Member] | Minimum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate	0.75%	0.75%
London Interbank Offered Rate (LIBOR) [Member] | Minimum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate						0.125%
London Interbank Offered Rate (LIBOR) [Member] | Maximum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate						1.00%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate						1.125%
Wells Fargo and Bank of America
Line of Credit Facility [Line Items]
Maturity date						Mar. 15, 2021
Wells Fargo and Bank of America | Line of Credit
Line of Credit Facility [Line Items]
Repayments of lines of credit				$ 242,500
Wells Fargo and Bank of America | Revolving Credit Facility | Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity												$ 300,000
Wells Fargo and Bank of America | Term Loan Facility | Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity												$ 300,000
Amortization of financing costs						$ 7,500				$ 18,800
Wells Fargo and Bank of America | First Amendment To Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 350,000
Line of Credit Facility, Increase (Decrease), Net					50,000
Wells Fargo and Bank of America | First Amendment To Credit Agreement | Term Loan Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity					93,800
Outstanding borrowings					$ 93,800
Wells Fargo and Bank of America | London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate						2.00%
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee rate range											0.125%
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Commitment fee rate range											0.20%
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | Revolving Credit Facility | Line of Credit
Line of Credit Facility [Line Items]
Outstanding borrowings	$ 0	$ 0					$ 0
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | Scenario 3 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Covenant Terms							not to exceed $50.0 million
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | Scenario 4 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Covenant Terms							not less than $75.0 million
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | Second Amendment To Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity				850,000
Line of Credit Facility, Increase (Decrease), Net				$ 500,000
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | Base Rate [Member] | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate											0.00%
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | Base Rate [Member] | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate											0.75%
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate											1.00%
WellsFargo,NationalAssociation,SunTrustBankandBankofAmerica,N.A. [Member] | London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate											1.75%
WellsFargo,NationalAssociation,TruistBank,BMOHarrisBankN.A.,SantanderBankN.A.,andBankofAmerica,N.A. [Member]
Line of Credit Facility [Line Items]
Maturity date							Jul. 21, 2023
WellsFargo,NationalAssociation,TruistBank,BMOHarrisBankN.A.,SantanderBankN.A.,andBankofAmerica,N.A. [Member] | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee rate range		0.25%
WellsFargo,NationalAssociation,TruistBank,BMOHarrisBankN.A.,SantanderBankN.A.,andBankofAmerica,N.A. [Member] | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Commitment fee rate range		0.35%
WellsFargo,NationalAssociation,TruistBank,BMOHarrisBankN.A.,SantanderBankN.A.,andBankofAmerica,N.A. [Member] | First Amended and Restated Credit Agreement [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 1,050,000	$ 1,050,000					$ 1,050,000
Line of Credit Facility, Increase (Decrease), Net		$ 200,000
WellsFargo,NationalAssociation,TruistBank,BMOHarrisBankN.A.,SantanderBankN.A.,andBankofAmerica,N.A. [Member] | Eurodollar [Member] | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate		1.50%
WellsFargo,NationalAssociation,TruistBank,BMOHarrisBankN.A.,SantanderBankN.A.,andBankofAmerica,N.A. [Member] | Eurodollar [Member] | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate		2.25%
WellsFargo,NationalAssociation,TruistBank,BMOHarrisBankN.A.,SantanderBankN.A.,andBankofAmerica,N.A. [Member] | Base Rate [Member] | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate		0.50%
WellsFargo,NationalAssociation,TruistBank,BMOHarrisBankN.A.,SantanderBankN.A.,andBankofAmerica,N.A. [Member] | Base Rate [Member] | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Applicable interest rate added to reference rate in order to compute variable interest rate		1.25%