Computation of Basic and Diluted Earnings Per Share for classes A, B, C and D Common Stockholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Basic and Diluted:
Net income attributable to UHS	$ 223,832	$ 206,055
Less: Net income attributable to unvested restricted share grants	(104)	(94)
Net income attributable to UHS – basic and diluted	$ 223,728	$ 205,961
Weighted average number of common shares - basic	94,226	96,585
Net effect of dilutive stock options and grants based on the treasury stock method	457	787
Weighted average number of common shares and equivalents - diluted	94,683	97,372
Earnings per basic share attributable to UHS:	$ 2.37	$ 2.13
Earnings per diluted share attributable to UHS:	$ 2.36	$ 2.12