Summary of Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill, Beginning Balance		$ 3,869,760	$ 3,844,628
Goodwill acquired during the period		127	5,926
Goodwill divested during the period		0	0
Adjustments to goodwill	[1]	12,828	19,206
Goodwill, Ending Balance		3,882,715	3,869,760
Acute Care Services
Goodwill [Line Items]
Goodwill, Beginning Balance		448,415	442,462
Goodwill acquired during the period		127	5,926
Goodwill divested during the period		0	0
Adjustments to goodwill	[1]	(1,521)	27
Goodwill, Ending Balance		447,021	448,415
Behavioral Health Services
Goodwill [Line Items]
Goodwill, Beginning Balance		3,421,345	3,402,166
Goodwill acquired during the period		0	0
Goodwill divested during the period		0	0
Adjustments to goodwill	[1]	14,349	19,179
Goodwill, Ending Balance		$ 3,435,694	$ 3,421,345

[1] The increases in the Behavioral Health Services’ goodwill consists primarily of foreign currency translation adjustments.