Debt (Additional Information) (Details) - USD ($)							3 Months Ended					15 Months Ended
	Aug. 12, 2021	Jul. 29, 2021	Mar. 01, 2021	Feb. 12, 2021	Mar. 24, 2020	Apr. 13, 2018	Mar. 31, 2024	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2016	Dec. 31, 2022	Jun. 30, 2021
Line of Credit Facility [Line Items]
Repayment of long-term debt								$ 291,000,000		$ 750,000
Letters of credit outstanding	$ 83,600,000							$ 153,400,000		68,400,000	$ 68,400,000		$ 68,400,000
Letter Of Credit Title Iv Disbursement Percentage											10.00%
Letter of credit, repayment period											5 years
Annual fee percentage								4.25%
Credit annual fee percentage reimbursement								2.00%
Commitment fee percentage								0.25%
Undrawn amount on letters of credit								$ 246,600,000
Line of Credit facility, initiation date						Apr. 13, 2018
Amortization of debt issuance costs								$ 17,858,000		392,000
Fronting fee percentage								0.125%
Interest Rate Swap
Line of Credit Facility [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax								$ (4,525,000)
Interest Rate Swap | Interest Expense [Member]
Line of Credit Facility [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax		$ (4,500,000)
Revolver [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 400,000,000
Term									5 years
Revolver [Member] | LIBOR Floor [Member]
Line of Credit Facility [Line Items]
Basic spread rate								0.75%
Revolver [Member] | LIBOR Floor [Member] | Minimum
Line of Credit Facility [Line Items]
Basic spread rate								3.75%
Revolver [Member] | LIBOR Floor [Member] | Maximum
Line of Credit Facility [Line Items]
Basic spread rate								4.25%
Revolver [Member] | Alternate Base Rate [Member] | Minimum
Line of Credit Facility [Line Items]
Basic spread rate								2.75%
Revolver [Member] | Alternate Base Rate [Member] | Maximum
Line of Credit Facility [Line Items]
Basic spread rate								3.25%
Prior Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity						$ 300,000,000
Line of credit facility, expiration date						Apr. 13, 2023
Long-term Line of Credit										$ 0			0
Debt Issuance Costs Write-off								$ 6,000,000
Prior Revolving Credit Facility [Member] | Interest Expense [Member]
Line of Credit Facility [Line Items]
Debt Issuance Costs Write-off								$ 6,000,000.0
Prior Revolving Credit Facility [Member] | Base Rate [Member] | Minimum
Line of Credit Facility [Line Items]
Application rate, percentage									0.75%
Prior Revolving Credit Facility [Member] | Base Rate [Member] | Maximum
Line of Credit Facility [Line Items]
Application rate, percentage									1.75%
Prior Revolving Credit Facility [Member] | Eurocurrency Rate [Member] | Minimum
Line of Credit Facility [Line Items]
Application rate, percentage								1.75%
Prior Revolving Credit Facility [Member] | Eurocurrency Rate [Member] | Maximum
Line of Credit Facility [Line Items]
Application rate, percentage								2.75%
Term Loan B
Line of Credit Facility [Line Items]
Debt instrument, face amount				$ 850,000,000
Debt Instrument, Issuance Price, Percent Of Principal Amount	99.00%
Debt Instrument, Issuance Discount, Percent	1.00%
Bridge
Line of Credit Facility [Line Items]
Debt Issuance Costs Write-off								$ 10,329,000
Bridge | Interest Expense [Member]
Line of Credit Facility [Line Items]
Debt Issuance Costs Write-off								$ 10,300,000
Senior Secured Notes Due 2028 And Term B Loan [Member]
Line of Credit Facility [Line Items]
Term									7 years
Cap percentage								20.00%
Senior Secured Notes Due 2028 And Term B Loan [Member] | Scenario, Plan [Member]
Line of Credit Facility [Line Items]
Total net leverage ratio							3.25%					4.00%
Senior Secured Notes Due 2028 [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount			$ 800,000,000
Fixed interest rate			5.50%
Percentage of notes issued on par value			100.00%
Redemption price, percentage of principal amount redeemed			100.00%
Debt covenant, percentage of principal amount of notes outstanding			25.00%
Senior Secured Notes Due 2028 [Member] | Accrued Liabilities
Line of Credit Facility [Line Items]
Debt Instrument, Accrued Interest								$ 3,700,000					14,700,000
Senior Secured Notes Due 2028 [Member] | 2024
Line of Credit Facility [Line Items]
Redemption price, percentage of principal amount redeemed			102.75%
Senior Secured Notes Due 2028 [Member] | 2025
Line of Credit Facility [Line Items]
Redemption price, percentage of principal amount redeemed			101.375%
Senior Secured Notes Due 2028 [Member] | 2026
Line of Credit Facility [Line Items]
Redemption price, percentage of principal amount redeemed			100.00%
Senior Secured Notes Due 2028 [Member] | Prior to March 1,2024
Line of Credit Facility [Line Items]
Redemption price percentage			105.50%
Senior Secured Notes Due 2028 [Member] | Maximum | Prior to March 1,2024
Line of Credit Facility [Line Items]
Redemption price, percentage of principal amount redeemed			40.00%
Term B Loan [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount	$ 850,000,000
Fixed interest rate								5.25%
Debt Instrument, Ticking Fee, Term				30 days
Debt Instrument, Ticking Fee, Percent				50.00%
Basic spread rate				4.50%
Principal payment	$ 2,125,000
Term B Loan [Member] | Accrued Liabilities
Line of Credit Facility [Line Items]
Accrued Ticking Fees													$ 11,300,000
Term B Loan [Member] | LIBOR Floor [Member]
Line of Credit Facility [Line Items]
Basic spread rate	0.75%			0.75%
Term B Loan [Member] | Alternate Base Rate [Member] | Minimum
Line of Credit Facility [Line Items]
Basic spread rate	3.00%
Term B Loan [Member] | Alternate Base Rate [Member] | Maximum
Line of Credit Facility [Line Items]
Basic spread rate	3.50%
Term B Loan [Member] | LIBOR
Line of Credit Facility [Line Items]
Basic spread rate				4.50%
Term B Loan [Member] | Eurocurrency Rate [Member] | Minimum
Line of Credit Facility [Line Items]
Basic spread rate	4.00%
Term B Loan [Member] | Eurocurrency Rate [Member] | Maximum
Line of Credit Facility [Line Items]
Basic spread rate	4.50%
Prior Term Loan B [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount						$ 300,000,000
Repayment of long-term debt	$ 291,000,000.0
Principal payment						$ 750,000
Interest rate for borrowings under the Term B Loan facility										3.15%			3.10%
Debt instrument, maturity date						Apr. 13, 2025
Prior Term Loan B [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basic spread rate								2.00%
Debt instrument, description of variable rate basis								base rate plus 2%
Prior Term Loan B [Member] | Eurocurrency Rate [Member]
Line of Credit Facility [Line Items]
Basic spread rate					3.00%			3.00%
Debt instrument, description of variable rate basis								LIBOR-equivalent rate plus 3%
Prior Term Loan B [Member] | Interest Rate Swap
Line of Credit Facility [Line Items]
Derivative, Fixed Interest Rate					0.946%
Derivative, Swaption Interest Rate								3.946%
Prior Term Loan B [Member] | Interest Rate Swap | LIBOR
Line of Credit Facility [Line Items]
Debt instrument, description of variable rate basis					one-month LIBOR
Prior Term Loan B [Member] | Interest Rate Swap | LIBOR | Minimum
Line of Credit Facility [Line Items]
Derivative, Floor Interest Rate					0.00%