Revolving Credit Facility (Details) - Credit And Guarantee Agreement - USD ($)		1 Months Ended
	Apr. 30, 2017	Apr. 30, 2019	Sep. 30, 2020	Feb. 29, 2020	Feb. 28, 2018
Revolving Credit Facility
Line of Credit Facility [Line Items]
Unused capacity, commitment fee (percent)	0.20%
Letter of Credit
Line of Credit Facility [Line Items]
Commitment fee (percent)	1.50%
Fronting fee (percent)	0.125%
Line of Credit
Line of Credit Facility [Line Items]
Covenant terms, minimum liquidity balance	$ 100,000,000.0
Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	600,000,000.0				$ 725,000,000.0
Debt issuance fees	$ 2,600,000				400,000
Debt instrument, term		5 years
Line of credit facility, accordion feature, increase limit				$ 275,000,000.0
Aggregate letters of credit outstanding amount			$ 45,700,000
Remaining borrowing capacity			$ 679,300,000
Line of Credit | Revolving Credit Facility | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)	1.50%
Line of Credit | Revolving Credit Facility | Base Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)	0.50%
Line of Credit | Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity					$ 187,500,000