| Document and Entity Information | Nov. 05, 2019 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 5, 2019 |
| Entity Registrant Name | Acadia Healthcare Company, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-35331 |
| 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 |
| Entity Information, Former Legal or Registered Name | Not Applicable |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001520697 |
| Title of 12(b) Security | Common Stock, $0.01 par value |
| Trading Symbol | ACHC |
| Security Exchange Name | NASDAQ |
