Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net income (loss) attributable to Acadia Healthcare Company, Inc.	$ 255,612	$ (21,667)	$ 273,139
Denominator:
Weighted average shares outstanding for basic earnings per share	91,621	90,949	89,680
Effects of dilutive instruments	438		1,875
Shares used in computing diluted earnings per common share	92,059	90,949	91,555
Basic Earnings (loss) per share attributable to Acadia Healthcare Company, Inc. stockholders:
Basic	$ 2.79	$ (0.24)	$ 3.05
Diluted Earnings (loss) per share attributable to Acadia Healthcare Company, Inc. stockholders:
Diluted	$ 2.78	$ (0.24)	$ 2.98

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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