Construction Partners, Inc. Quarterly report [Sections 13 or 15(d)]

Quarterly report [Sections 13 or 15(d)]

Debt - Additional Information (Details)

Debt - Additional Information (Details)		3 Months Ended	6 Months Ended
Debt - Additional Information (Details)	Nov. 01, 2024 USD ($)	Dec. 31, 2024 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2026	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2024 USD ($)	Jun. 30, 2022 USD ($)
Debt Instrument [Line Items]
Fixed coverage ratio			3.29					3.18
Leverage ratio			3.23					1.80
Notional amount			$ 300,000,000					$ 300,000,000
Fair value of interest rate swaps			11,900,000					11,600,000
Proceeds from revolving credit facility			145,000,000	$ 90,000,000
Term Loan A
Debt Instrument [Line Items]
Long-term debt			$ 381,600,000					392,200,000
Credit Agreement \| Minimum
Debt Instrument [Line Items]
Fixed coverage ratio			1.20
Term Loan B
Debt Instrument [Line Items]
Long-term debt			$ 847,900,000					$ 0
Secured Debt \| Term Loan A/Revolver Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity									$ 375,000,000
Secured Debt \| Initial Term Loan \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity									250,000,000
Secured Debt \| Incremental Term Loan \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity									125,000,000
Secured Debt \| Delayed Draw Term Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity									50,000,000
Secured Debt \| Term Loan - 11 Quarters \| Revolving Credit Facility
Debt Instrument [Line Items]
Principal repayment rate			1.25%
Secured Debt \| Term Loan - 8 Quarters \| Revolving Credit Facility
Debt Instrument [Line Items]
Principal repayment rate			1.875%
Secured Debt \| Term Loan A \| Revolving Credit Facility \| Daily Simple SOFR
Debt Instrument [Line Items]
Basis spread			0.10%
Secured Debt \| Term Loan A \| Revolving Credit Facility \| Term SOFR
Debt Instrument [Line Items]
Basis spread			0.10%
Secured Debt \| Credit Agreement \| Revolving Credit Facility \| Maximum
Debt Instrument [Line Items]
Leverage ratio								3.50
Secured Debt \| Credit Agreement \| Revolving Credit Facility \| Maximum \| Forecast
Debt Instrument [Line Items]
Leverage ratio					3.50	4.00	4.50
Secured Debt \| Term Loan B Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity	$ 850,000,000
Principal repayment rate	0.25%
Proceeds from revolving credit facility	$ 850,000,000
Secured Debt \| Term Loan B Credit Agreement \| Revolving Credit Facility \| Term SOFR \| Variable Rate Component One
Debt Instrument [Line Items]
Basis spread	1.00%
Secured Debt \| Term Loan B Credit Agreement \| Revolving Credit Facility \| Term SOFR \| Variable Rate Component Two
Debt Instrument [Line Items]
Basis spread	2.50%
Secured Debt \| Term Loan B Credit Agreement \| Revolving Credit Facility \| Fed Funds Effective Rate Overnight Index Swap Rate
Debt Instrument [Line Items]
Basis spread	0.50%
Secured Debt \| Term Loan B Credit Agreement \| Revolving Credit Facility \| Base Rate \| Variable Rate Component One
Debt Instrument [Line Items]
Basis spread	1.00%
Secured Debt \| Term Loan B Credit Agreement \| Revolving Credit Facility \| Base Rate \| Variable Rate Component Two
Debt Instrument [Line Items]
Basis spread	1.50%
Secured Debt \| Bridge Facility
Debt Instrument [Line Items]
Interest expense		$ 3,100,000
Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity			$ 400,000,000
Long-term debt			145,000,000					$ 122,900,000
Remaining borrowing capacity			$ 248,400,000					$ 268,800,000
Revolving Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity									$ 400,000,000