Financial Information for the Company and Its Subsidiaries - Summary of Condensed Consolidating Statement of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Revenue before provision for doubtful accounts	$ 627,183	$ 374,158
Provision for doubtful accounts	(10,370)	(8,375)
Revenue	616,813	365,783
Salaries, wages and benefits	341,028	205,871
Professional fees	39,991	22,427
Supplies	26,685	16,254
Rents and leases	14,806	5,886
Other operating expenses	70,247	40,527
Depreciation and amortization	27,975	13,104
Interest expense, net	37,714	22,146
Gain on foreign currency derivatives	(410)	(53)
Transaction-related expenses	26,298	18,416
Total expenses	584,334	344,578
(Loss) income from continuing operations before income taxes	32,479	21,205
(Benefit from) provision for income taxes	7,110	6,613
Income (loss) from continuing operations	25,369	14,592
Income from discontinued operations, net of income taxes		2
Net income (loss)	25,369	14,594
Net loss attributable to noncontrolling interests	319
Net income (loss) attributable to Acadia Healthcare Company, Inc.	25,688	14,594
Other comprehensive loss:
Foreign currency translation loss	(48,415)	(29,389)
Other comprehensive loss	(48,415)	(29,389)
Comprehensive loss attributable to Acadia Healthcare Company. Inc.	(22,727)	(14,795)
Consolidating Adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
Equity in earnings of subsidiaries	(40,869)	(25,987)
Income (loss) from continuing operations	(40,869)	(25,987)
Net income (loss)	(40,869)	(25,987)
Net income (loss) attributable to Acadia Healthcare Company, Inc.	(40,869)
Other comprehensive loss:
Comprehensive loss attributable to Acadia Healthcare Company. Inc.	(40,869)	(25,987)
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Salaries, wages and benefits	6,956	3,894
Interest expense, net	13,433	12,948
Gain on foreign currency derivatives	(410)	(53)
Total expenses	19,979	16,789
(Loss) income from continuing operations before income taxes	(19,979)	(16,789)
Equity in earnings of subsidiaries	40,869	25,987
(Benefit from) provision for income taxes	(4,479)	(5,396)
Income (loss) from continuing operations	25,369	14,594
Net income (loss)	25,369	14,594
Net income (loss) attributable to Acadia Healthcare Company, Inc.	25,369
Other comprehensive loss:
Comprehensive loss attributable to Acadia Healthcare Company. Inc.	25,369	14,594
Combined Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue before provision for doubtful accounts	402,934	287,765
Provision for doubtful accounts	(9,342)	(7,419)
Revenue	393,592	280,346
Salaries, wages and benefits	211,033	155,699
Professional fees	22,677	16,485
Supplies	18,462	13,009
Rents and leases	8,577	5,117
Other operating expenses	48,849	25,115
Depreciation and amortization	12,751	8,711
Interest expense, net	16,093	5,721
Transaction-related expenses	21,435	18,416
Total expenses	359,877	248,273
(Loss) income from continuing operations before income taxes	33,715	32,073
(Benefit from) provision for income taxes	7,407	10,497
Income (loss) from continuing operations	26,308	21,576
Income from discontinued operations, net of income taxes		2
Net income (loss)	26,308	21,578
Net income (loss) attributable to Acadia Healthcare Company, Inc.	26,308
Other comprehensive loss:
Comprehensive loss attributable to Acadia Healthcare Company. Inc.	26,308	21,578
Combined Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue before provision for doubtful accounts	224,249	86,393
Provision for doubtful accounts	(1,028)	(956)
Revenue	223,221	85,437
Salaries, wages and benefits	123,039	46,278
Professional fees	17,314	5,942
Supplies	8,223	3,245
Rents and leases	6,229	769
Other operating expenses	21,398	15,412
Depreciation and amortization	15,224	4,393
Interest expense, net	8,188	3,477
Transaction-related expenses	4,863
Total expenses	204,478	79,516
(Loss) income from continuing operations before income taxes	18,743	5,921
(Benefit from) provision for income taxes	4,182	1,512
Income (loss) from continuing operations	14,561	4,409
Net income (loss)	14,561	4,409
Net loss attributable to noncontrolling interests	319
Net income (loss) attributable to Acadia Healthcare Company, Inc.	14,880
Other comprehensive loss:
Foreign currency translation loss	(48,415)	(29,389)
Other comprehensive loss	(48,415)	(29,389)
Comprehensive loss attributable to Acadia Healthcare Company. Inc.	$ (33,535)	$ (24,980)