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

Quarterly report [Sections 13 or 15(d)]

Share-Based Compensation - Additional Information (Details)

Share-Based Compensation - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		24 Months Ended
	Mar. 31, 2024 shares	Jun. 30, 2025 USD ($) installment shares	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) installment shares	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) installment shares	Sep. 30, 2024 USD ($)	May 31, 2021 shares	Sep. 30, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recorded upon vesting of awards \| $		$ 8,564	$ 4,039	$ 27,961	$ 10,586
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of stock grant awards (in shares)				136,917
Class B Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of stock grant awards (in shares)				61,000
Market-Based Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate grant date fair value of shares awarded \| $		9,800		$ 9,800		$ 9,800
Compensation expense recorded upon vesting of awards \| $		0		$ 9,800
Market-Based Restricted Stock \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)				79,000
Market-Based Restricted Stock \| Class B Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)				61,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate grant date fair value of shares awarded \| $		$ 4,100		$ 4,100		$ 4,100
Unrecognized compensation expense, period for recognition (years)				2 years 3 months 18 days
Performance Shares \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Forecasted unvested restricted shares of Class A common stock (in shares)		366,793		366,793		366,793
Unrecognized compensation expense at fiscal year-end \| $		$ 5,800		$ 5,800		$ 5,800
Shares issued (in shares)				215,917
Performance Shares \| Class A Common Stock \| Certain members of management
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)				73,603
Forecasted unvested restricted shares of Class A common stock (in shares)		55,202		55,202		55,202
Performance Shares \| Class B Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)				61,000
Performance Shares \| Class B Common Stock \| Certain members of management
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)				61,000
Liability classified awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recorded upon vesting of awards \| $		$ 4,076	1,092	$ 5,916	1,974
Current liability for cash-settled restricted stock units \| $		7,700		7,700		$ 7,700	$ 3,700
Liability classified awards \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recorded upon vesting of awards \| $		4,100		$ 5,900
Unrecognized compensation expense, period for recognition (years)				3 years 2 months 12 days
Shares issued (in shares)				80,614
Unrecognized compensation expense \| $		$ 9,500		$ 9,500		$ 9,500
Requisite service period, number of equal annual installments \| installment		4		4		4
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares offered under the ESPP (in shares)								1,000,000
Compensation expense recorded upon vesting of awards \| $		$ 584	$ 54	$ 1,098	$ 380
Shares issued (in shares)						84,601
Minimum \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of final number of of common stock issuable upon vesting of performance stock units				0
Maximum \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of final number of of common stock issuable upon vesting of performance stock units				1.50
Percentage increase (decrease) of awards granted due to total shareholder return ranking				0.15
Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares offered under the ESPP (in shares)									2,000,000
Additional shares authorized (in shares)	1,000,000
Shares available for issuance (in shares)		901,350		901,350		901,350
Equity Incentive Plan \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recorded upon vesting of awards \| $		$ 1,100		$ 2,800
Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares offered under the ESPP (in shares)	2,000,000
Shares available for issuance (in shares)		1,891,000		1,891,000		1,891,000