Equity Offerings - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands					6 Months Ended
	Feb. 16, 2016	Jan. 12, 2016	May 11, 2015	Feb. 11, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 03, 2016	Dec. 31, 2015
Equity [Line Items]
Common stock, shares authorized					180,000,000		180,000,000	90,000,000
Common stock offered		11,500,000	5,175,000		86,571,040			70,745,746
Common stock offer price		$ 61.00	$ 66.50		$ 0.01			$ 0.01
Underwriting discount amount		$ 15,800	$ 12,000
Additional offering-related costs		700	800
Net proceeds from sale of shares		$ 685,000	$ 331,300		$ 216,882	$ 380,210
CRC Health Group, Inc [Member]
Equity [Line Items]
Total consideration related to acquisition				$ 1,300,000
Shares issued for acquisition				5,975,326
Priory [Member]
Equity [Line Items]
Total consideration related to acquisition	$ 2,200,000
Shares issued for acquisition	4,033,561