Credit Facility - Narrative (Details)	Sep. 05, 2018	Sep. 01, 2017 USD ($)	Jul. 31, 2020	Jul. 31, 2018	Aug. 31, 2017 USD ($)
Minimum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Commitment fee percentage on unused portion of the Facility		0.20%
Maximum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Commitment fee percentage on unused portion of the Facility		0.35%
Prior Credit Facility | Revolving Credit Facility | Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity					$ 800,000,000.0
Credit Facility
Line of Credit Facility [Line Items]
Weighted average interest rate				4.07%
Deferred financing costs		$ 18,700,000
Credit Facility | Line of Credit
Line of Credit Facility [Line Items]
Deferred financing costs		5,200,000
Credit Facility | Term Loan
Line of Credit Facility [Line Items]
Debt instrument, face amount		800,000,000.0
Deferred financing costs		13,400,000
Credit Facility | Revolving Credit Facility | Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity		900,000,000.0
Borrowing capacity after initial year of term		800,000,000.0
Credit Facility | Standby Letters of Credit
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity		300,000,000.0
Credit Facility | Swing Line Loan
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity		$ 75,000,000.0
Credit Facility | Minimum
Line of Credit Facility [Line Items]
Fixed charge coverage ratio		1.50
Credit Facility | Maximum
Line of Credit Facility [Line Items]
Leverage ratio		4.75
Leverage ratio election option for four fiscal quarters in event of material acquisition		3.75
Credit Facility | Maximum | Forecast
Line of Credit Facility [Line Items]
Leverage ratio			3.50
Credit Facility | Eurodollar | Forecast
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.25%
Credit Facility | Eurodollar | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
Credit Facility | Eurodollar | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate		2.25%
Credit Facility | Base Rate | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.00%
Credit Facility | Base Rate | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.25%