Revenue - Schedule of U.S. Revenue and Percentage Generated by Each Payor Type (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Revenue	$ 760,617	$ 742,241
U.S. Facilities [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Revenue	$ 487,960	$ 462,405
Revenue, Percentage	100.00%	100.00%
U.S. Facilities [Member] | Commercial [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Revenue	$ 139,427	$ 137,619
Revenue, Percentage	28.60%	29.80%
U.S. Facilities [Member] | Medicare [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Revenue	$ 72,616	$ 67,214
Revenue, Percentage	14.90%	14.50%
U.S. Facilities [Member] | Medicaid [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Revenue	$ 239,191	$ 213,336
Revenue, Percentage	49.00%	46.10%
U.S. Facilities [Member] | Self-Pay [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Revenue	$ 31,732	$ 36,907
Revenue, Percentage	6.50%	8.00%
U.S. Facilities [Member] | Other [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Revenue	$ 4,994	$ 7,329
Revenue, Percentage	1.00%	1.60%