Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Other Comprehensive Loss [Member]	Earnings (Accumulated Deficit) [Member]
Balance at Dec. 31, 2014	$ 880,965	$ 592	$ 847,301	$ (68,370)	$ 101,442
Balance, shares at Dec. 31, 2014		59,212,000
Common stock issued under stock incentive plans	1,815	$ 4	1,811
Common stock issued under stock incentive plans, shares		384,000
Common stock withheld for minimum statutory taxes	(9,577)		(9,577)
Equity-based compensation expense	20,472		20,472
Excess tax benefit from equity awards	309		309
Issuance of common stock, net	711,517	$ 111	711,406
Issuance of common stock, net, shares		11,150,000
Other comprehensive gain (loss)	(36,277)			(36,277)
Other	1,250		1,250
Net income attributable to Acadia Healthcare Company, Inc. stockholders	112,554				112,554
Balance at Dec. 31, 2015	1,683,028	$ 707	1,572,972	(104,647)	213,996
Balance, shares at Dec. 31, 2015		70,746,000
Common stock issued under stock incentive plans	$ 1,384	$ 5	1,379
Common stock issued under stock incentive plans, shares	57,397	408,000
Common stock withheld for minimum statutory taxes	$ (10,230)		(10,230)
Equity-based compensation expense	28,345		28,345
Issuance of common stock, net	901,979	$ 155	901,824
Issuance of common stock, net, shares		15,534,000
Other comprehensive gain (loss)	(444,923)			(444,923)
Other	1,998		1,998
Net income attributable to Acadia Healthcare Company, Inc. stockholders	6,143				6,143
Balance at Dec. 31, 2016	$ 2,167,724	$ 867	2,496,288	(549,570)	220,139
Balance, shares at Dec. 31, 2016	86,688,199	86,688,000
Common stock issued under stock incentive plans	$ 2,069	$ 4	2,065
Common stock issued under stock incentive plans, shares	87,367	372,000
Common stock withheld for minimum statutory taxes	$ (5,524)		(5,524)
Equity-based compensation expense	23,467		23,467
Cumulative effect of change in accounting principle	8,599				8,599
Other comprehensive gain (loss)	175,452			175,452
Other	1,249		1,249
Net income attributable to Acadia Healthcare Company, Inc. stockholders	199,835				199,835
Balance at Dec. 31, 2017	$ 2,572,871	$ 871	$ 2,517,545	$ (374,118)	$ 428,573
Balance, shares at Dec. 31, 2017	87,060,114	87,060,000