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Annual coverage limit provided by the insurance arrangement for malpractice claims.

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Maximum coverage per malpractice claim provided by the insurance arrangement.

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Amount of risk reinsured in excess of stated retention per company policy.

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Commitments and Contingencies - Additional Information (Detail)		3 Months Ended
	Jan. 15, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 Facility	Dec. 31, 2018 USD ($)
Loss Contingencies [Line Items]
Maximum professional liability aggregate policy limit		$ 75,000,000.0
Pioneer Behavioral Health [Member]
Loss Contingencies [Line Items]
Legal settlement amount paid	$ 3,100,000
West Virginia [Member]
Loss Contingencies [Line Items]
Number of comprehensive treatment centers operate \| Facility			7
West Virginia [Member] \| Other Accrued Liabilities [Member]
Loss Contingencies [Line Items]
Litigation reserve				$ 19,000,000.0
Maximum [Member]
Loss Contingencies [Line Items]
Maximum self insured professional liability limit per claim		3,000,000.0
Minimum [Member]
Loss Contingencies [Line Items]
Maximum professional liability retention limit		$ 3,000,000.0