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			6 Months Ended		21 Months Ended
	Mar. 31, 2024 shares	Mar. 31, 2025 USD ($) installment shares	Dec. 31, 2024 USD ($)	Mar. 31, 2024 USD ($) shares	Mar. 31, 2025 USD ($) installment shares	Mar. 31, 2024 USD ($) shares	Mar. 31, 2025 USD ($) 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 \| $		$ 4,672		$ 3,553	$ 19,397	$ 6,599
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]
Compensation expense recorded upon vesting of awards \| $					$ 9,800
Aggregate grant date fair value of shares awarded \| $		9,800			$ 9,800		$ 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 \| $		$ 3,700			$ 3,700		$ 3,700
Unrecognized compensation expense, period for recognition (years)					2 years 2 months 12 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)		226,102			226,102		226,102
Unrecognized compensation expense at fiscal year-end \| $		$ 6,500			$ 6,500		$ 6,500
Shares issued (in shares)					210,520
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 \| $		$ 1,111		776	$ 1,840	882
Current liability for cash-settled restricted stock units \| $		3,700			3,700		$ 3,700	$ 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 \| $			$ 1,800		$ 1,100
Unrecognized compensation expense, period for recognition (years)					3 years 2 months 12 days
Shares issued (in shares)					77,634
Unrecognized compensation expense \| $		$ 7,800			$ 7,800		$ 7,800
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 \| $		$ 192		$ 221	$ 514	378
Shares issued (in shares)							71,022
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)		961,350			961,350		961,350
Equity Incentive Plan \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recorded upon vesting of awards \| $					$ 1,700	$ 600
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			2,000,000		2,000,000
Shares available for issuance (in shares)		1,891,000			1,891,000		1,891,000