Summary of Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Beginning Balance		$ 3,825,157	$ 3,784,106
Goodwill acquired during the period		45,090	80
Goodwill divested during the period		(2,135)
Adjustments to goodwill	[1]	(23,484)	40,971
Goodwill, Ending Balance		3,844,628	3,825,157
Acute Care Services
Goodwill [Line Items]
Goodwill, Beginning Balance		441,511	440,294
Goodwill acquired during the period		917	80
Goodwill divested during the period		0
Adjustments to goodwill	[1]	34	1,137
Goodwill, Ending Balance		442,462	441,511
Behavioral Health Services
Goodwill [Line Items]
Goodwill, Beginning Balance		3,383,646	3,343,812
Goodwill acquired during the period		44,173	0
Goodwill divested during the period		(2,135)
Adjustments to goodwill	[1]	(23,518)	39,834
Goodwill, Ending Balance		$ 3,402,166	$ 3,383,646

[1] The increase/(decrease) in the Behavioral Health Services’ goodwill consists primarily of foreign currency translation adjustments.