Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic and diluted:
Net Income	$ 307,734	$ 244,092	$ 256,504	$ 144,460	$ 248,010	$ 100,870	$ 241,265	$ 237,398	$ 952,790	$ 827,543	$ 797,883
Less: Net income attributable to noncontrolling interest	$ 974	$ (2,813)	$ (4,575)	$ (2,423)	$ (2,834)	$ (3,680)	$ (2,945)	$ (3,230)	(8,837)	(12,689)	(18,178)
Less: Net income attributable to unvested restricted share grants									(2,981)	(2,028)	(1,091)
Net income attributable to UHS—basic and diluted									$ 940,972	$ 812,826	$ 778,614
Basic earnings per share attributable to UHS:
Weighted average number of common shares—basic									85,061	88,762	93,276
Total basic earnings per share	$ 3.63	$ 2.84	$ 2.97	$ 1.64	$ 2.81	$ 1.10	$ 2.67	$ 2.57	$ 11.06	$ 9.16	$ 8.35
Diluted earnings per share attributable to UHS:
Weighted average number of common shares—basic									85,061	88,762	93,276
Net effect of dilutive stock options and grants based on the treasury stock method									526	278	474
Weighted average number of common shares and equivalents—diluted									85,587	89,040	93,750
Total diluted earnings per share	$ 3.60	$ 2.82	$ 2.95	$ 1.64	$ 2.79	$ 1.10	$ 2.66	$ 2.57	$ 10.99	$ 9.13	$ 8.31