Segment Reporting (Parenthetical) (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net revenues		$ 2,648,913	$ 2,541,864	$ 8,017,782	$ 7,767,078
Total assets		11,273,585	10,639,360	11,273,585	10,639,360	$ 10,761,828
Behavioral Health Services
Segment Reporting Information [Line Items]
Net revenues	[1]	1,262,472	1,224,548	3,774,551	3,685,230
Total assets	[1]	6,871,765	6,610,811	6,871,765	6,610,811
Behavioral Health Services | Located in U.K.
Segment Reporting Information [Line Items]
Net revenues		130,000	111,000	364,000	317,000
Total assets		$ 1,231,000	$ 1,094,000	$ 1,231,000	$ 1,094,000

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $130 million and $111 million for the three-month periods ended September 30, 2018 and 2017, respectively, and approximately $364 million and $317 million for the nine-month periods ended September 30, 2018 and 2017 respectively. Total assets at our U.K. behavioral health care facilities were approximately $1.231 billion and $1.094 billion as of September 30, 2018 and 2017, respectively.