Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 05, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Trading Symbol	ACHC
Entity Registrant Name	Acadia Healthcare Company, Inc.
Entity Central Index Key	0001520697
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $.01 par value
Security Exchange Name	NASDAQ
Entity File Number	001-35331
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-2492228
Entity Address, Address Line One	6100 Tower Circle
Entity Address, Address Line Two	Suite 1000
Entity Address, City or Town	Franklin
Entity Address, State or Province	TN
Entity Address, Postal Zip Code	37067
City Area Code	615
Local Phone Number	861-6000
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		88,942,499