Financial Information for the Company and Its Subsidiaries - Summary of Condensed Consolidating Statement of Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Revenue before provision for doubtful accounts	$ 767,054	$ 461,798	$ 1,394,237	$ 835,956
Provision for doubtful accounts	(10,506)	(8,138)	(20,876)	(16,513)
Revenue	756,548	453,660	1,373,361	819,443
Salaries, wages and benefits	408,287	243,302	749,315	449,173
Professional fees	50,292	30,029	90,283	52,456
Supplies	31,209	20,542	57,894	36,796
Rents and leases	20,467	8,211	35,273	14,097
Other operating expenses	80,955	51,128	151,202	91,655
Depreciation and amortization	36,752	14,926	64,727	28,030
Interest expense, net	48,758	28,049	86,472	50,195
Loss (gain) on foreign currency derivatives	(98)	961	(508)	908
Transaction-related expenses	6,074	7,157	32,372	25,573
Total expenses	682,696	404,305	1,267,030	748,883
(Loss) income from continuing operations before income taxes	73,852	49,355	106,331	70,560
(Benefit from) provision for income taxes	18,261	15,512	25,371	22,125
Income (loss) from continuing operations	55,591	33,843	80,960	48,435
Income from discontinued operations, net of income taxes		1		3
Net income (loss)	55,591	33,844	80,960	48,438
Net loss attributable to noncontrolling interests	854		1,173
Net income (loss) attributable to Acadia Healthcare Company, Inc.	56,445	33,844	82,133	48,438
Other comprehensive income:
Foreign currency translation (loss) gain	(213,468)	46,173	(261,883)	16,784
Gain on derivative instruments	23,919		23,919
Other comprehensive income	(189,549)	46,173	(237,964)	16,784
Comprehensive (loss) income attributable to Acadia Healthcare Company, Inc.	(133,104)	80,017	(155,831)	65,222
Consolidating Adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
Equity in earnings of subsidiaries	(67,943)	(50,281)	(108,812)	(76,268)
Income (loss) from continuing operations	(67,943)	(50,281)	(108,812)	(76,268)
Net income (loss)	(67,943)	(50,281)	(108,812)	(76,268)
Net income (loss) attributable to Acadia Healthcare Company, Inc.	(67,943)		(108,812)
Other comprehensive income:
Comprehensive (loss) income attributable to Acadia Healthcare Company, Inc.	(67,943)	(50,281)	(108,812)	(76,268)
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Salaries, wages and benefits	6,888	5,355	13,844	9,249
Interest expense, net	10,631	18,106	24,064	31,054
Loss (gain) on foreign currency derivatives	(98)	961	(508)	908
Total expenses	17,421	24,422	37,400	41,211
(Loss) income from continuing operations before income taxes	(17,421)	(24,422)	(37,400)	(41,211)
Equity in earnings of subsidiaries	67,943	50,281	108,812	76,268
(Benefit from) provision for income taxes	(5,069)	(7,985)	(9,548)	(13,381)
Income (loss) from continuing operations	55,591	33,844	80,960	48,438
Net income (loss)	55,591	33,844	80,960	48,438
Net income (loss) attributable to Acadia Healthcare Company, Inc.	55,591		80,960
Other comprehensive income:
Gain on derivative instruments	23,919		23,919
Other comprehensive income	23,919		23,919
Comprehensive (loss) income attributable to Acadia Healthcare Company, Inc.	79,510	33,844	104,879	48,438
Combined Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue before provision for doubtful accounts	422,232	363,851	825,166	651,616
Provision for doubtful accounts	(9,593)	(7,566)	(18,935)	(14,985)
Revenue	412,639	356,285	806,231	636,631
Salaries, wages and benefits	212,944	183,490	423,977	339,189
Professional fees	23,150	22,579	45,827	39,064
Supplies	19,527	16,929	37,989	29,938
Rents and leases	8,521	7,402	17,098	12,519
Other operating expenses	51,100	43,145	99,949	75,392
Depreciation and amortization	14,216	10,551	26,967	19,262
Interest expense, net	22,043	5,882	38,136	11,603
Transaction-related expenses	4,189	2,946	25,624	21,362
Total expenses	355,690	292,924	715,567	548,329
(Loss) income from continuing operations before income taxes	56,949	63,361	90,664	88,302
(Benefit from) provision for income taxes	16,186	20,734	23,593	29,251
Income (loss) from continuing operations	40,763	42,627	67,071	59,051
Income from discontinued operations, net of income taxes		1		3
Net income (loss)	40,763	42,628	67,071	59,054
Net income (loss) attributable to Acadia Healthcare Company, Inc.	40,763		67,071
Other comprehensive income:
Comprehensive (loss) income attributable to Acadia Healthcare Company, Inc.	40,763	42,628	67,071	59,054
Combined Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue before provision for doubtful accounts	344,822	97,947	569,071	184,340
Provision for doubtful accounts	(913)	(572)	(1,941)	(1,528)
Revenue	343,909	97,375	567,130	182,812
Salaries, wages and benefits	188,455	54,457	311,494	100,735
Professional fees	27,142	7,450	44,456	13,392
Supplies	11,682	3,613	19,905	6,858
Rents and leases	11,946	809	18,175	1,578
Other operating expenses	29,855	7,983	51,253	16,263
Depreciation and amortization	22,536	4,375	37,760	8,768
Interest expense, net	16,084	4,061	24,272	7,538
Transaction-related expenses	1,885	4,211	6,748	4,211
Total expenses	309,585	86,959	514,063	159,343
(Loss) income from continuing operations before income taxes	34,324	10,416	53,067	23,469
(Benefit from) provision for income taxes	7,144	2,763	11,326	6,255
Income (loss) from continuing operations	27,180	7,653	41,741	17,214
Net income (loss)	27,180	7,653	41,741	17,214
Net loss attributable to noncontrolling interests	854		1,173
Net income (loss) attributable to Acadia Healthcare Company, Inc.	28,034		42,914
Other comprehensive income:
Foreign currency translation (loss) gain	(213,468)	46,173	(261,883)	16,784
Other comprehensive income	(213,468)	46,173	(261,883)	16,784
Comprehensive (loss) income attributable to Acadia Healthcare Company, Inc.	$ (185,434)	$ 53,826	$ (218,969)	$ 33,998