Fair Value Measurements - Carrying Amounts and Fair Values of Company's Amended and Restated Senior Credit Facilities and Contingent Consideration Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other long-term debt	$ 5,676	$ 5,953
Derivative instrument assets	46,304	60,524
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other long-term debt	5,677	5,953
Derivative instrument assets	46,304	60,524
Carrying Amount [Member] \| Amended and Restated Senior Credit Facility [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Secured	1,779,357	1,715,338
Carrying Amount [Member] \| 6.125% Senior Notes Due 2021 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Notes	148,803	148,657
Carrying Amount [Member] \| 5.125% Senior Notes Due 2022 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Notes	297,147	296,946
Carrying Amount [Member] \| 5.625% Senior Notes Due 2023 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Notes	643,651	643,289
Carrying Amount [Member] \| 6.500% Senior Notes due 2024 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Notes	383,577	383,304
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative instrument assets	46,304	60,524
Other long-term debt	5,677	5,953
Fair Value [Member] \| Amended and Restated Senior Credit Facility [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amended and Restated Senior Credit Facility	1,779,537	1,715,338
Fair Value [Member] \| 6.125% Senior Notes Due 2021 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Notes	148,803	147,542
Fair Value [Member] \| 5.125% Senior Notes Due 2022 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Notes	297,890	283,583
Fair Value [Member] \| 5.625% Senior Notes Due 2023 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Notes	647,674	609,516
Fair Value [Member] \| 6.500% Senior Notes due 2024 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior Notes	$ 394,125	$ 369,888

Other long term debt fair value.

No definition available.

Name:	achc_OtherLongTermDebtFairValue
Namespace Prefix:	achc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of the assets arising from derivative contracts and hedging activities, which are expected to be converted into cash or otherwise disposed of after a year or beyond the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_DerivativeInstrumentsAndHedgesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of contractual arrangement with a lender under which borrowings can be made up to a specific amount at any point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LinesOfCreditFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of notes payable.

+ References

+ Details

Name:	us-gaap_NotesPayableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_OtherLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_SeniorNotes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=achc_AmendedAndRestatedCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=achc_SixPointOneTwoFivePercentSeniorNotesDueTwoThousandTwentyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=achc_FivePointOneTwoFivePercentageSeniorNotesDueInTwoThousandTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=achc_FivePointSixTwoFivePercentageSeniorNotesDueTwoThousandTwentyThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=achc_SixPointFiveZeroZeroPercentSeniorNotesDueTwoThousandAndTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: