Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Redeemable Noncontrolling Interest	Class A	Class B	Class C	Class D	Cumulative Dividends	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	UHS Common Stockholders' Equity	Noncontrolling Interest
Balance at Dec. 31, 2019	$ 5,578,871		$ 66	$ 794	$ 7	$ 0	$ (462,159)	$ 5,933,504	$ 31,893	$ 5,504,105	$ 74,766
Balance at Dec. 31, 2019		$ 4,333
Common Stock
Issued/(converted)	9,729			3				9,726		9,729
Repurchased	(200,098)			(20)				(200,078)		(200,098)
Restricted share-based compensation expense	6,958							6,958		6,958
Dividends paid and accrued	(17,344)						(17,344)			(17,344)
Stock option expense	41,565							41,565		41,565
Distributions to noncontrolling interests	(14,675)	(500)									(14,675)
Purchase of noncontrolling interest / Purchase of ownership interests by minority members	(547)										(547)
Other	3,300										3,300
Comprehensive income:
Net income to UHS / noncontrolling interests	644,711							635,245		635,245	9,466
Net income attributable to redeemable noncontrolling interest		344
Foreign currency translation adjustments, net of income tax	(17,372)								(17,372)	(17,372)
Subtotal - comprehensive income	627,339							635,245	(17,372)	617,873	9,466
Subtotal attributable to redeemable noncontrolling interest		344
Balance at Sep. 30, 2020	6,035,098		66	777	7	0	(479,503)	6,426,920	14,521	5,962,788	72,310
Balance at Sep. 30, 2020		4,177
Balance at Jun. 30, 2020	5,761,572		66	777	7	0	(479,503)	6,166,722	578	5,688,647	72,925
Balance at Jun. 30, 2020		4,287
Common Stock
Issued/(converted)	3,766							3,766		3,766
Repurchased	(44)							(44)		(44)
Restricted share-based compensation expense	2,209							2,209		2,209
Stock option expense	12,988							12,988		12,988
Distributions to noncontrolling interests	(6,290)										(6,290)
Purchase of noncontrolling interest / Purchase of ownership interests by minority members	(547)										(547)
Other	3,300										3,300
Comprehensive income:
Net income to UHS / noncontrolling interests	244,201							241,279		241,279	2,922
Net income attributable to redeemable noncontrolling interest		(110)
Foreign currency translation adjustments, net of income tax	13,943								13,943	13,943
Subtotal - comprehensive income	258,144							241,279	13,943	255,222	2,922
Subtotal attributable to redeemable noncontrolling interest		(110)
Balance at Sep. 30, 2020	6,035,098		66	777	7	0	(479,503)	6,426,920	14,521	5,962,788	72,310
Balance at Sep. 30, 2020		4,177
Balance at Dec. 31, 2020	6,401,967		66	778	7	0	(479,503)	6,747,678	48,120	6,317,146	84,821
Balance at Dec. 31, 2020		4,569
Common Stock
Issued/(converted)	10,109			5				10,104		10,109
Repurchased	(788,539)			(51)				(788,488)		(788,539)
Restricted share-based compensation expense	9,583							9,583		9,583
Dividends paid and accrued	(50,343)						(50,343)			(50,343)
Stock option expense	44,825							44,825		44,825
Distributions to noncontrolling interests	(5,541)	(203)									(5,541)
Purchase of noncontrolling interest / Purchase of ownership interests by minority members	13,762										13,762
Comprehensive income:
Net income to UHS / noncontrolling interests	753,201							752,466		752,466	735
Net income attributable to redeemable noncontrolling interest		520
Foreign currency translation adjustments, net of income tax	(21,226)								(21,226)	(21,226)
Subtotal - comprehensive income	731,975							752,466	(21,226)	731,240	735
Subtotal attributable to redeemable noncontrolling interest		520
Balance at Sep. 30, 2021	6,367,798		66	732	7	0	(529,846)	6,776,168	26,894	6,274,021	93,777
Balance at Sep. 30, 2021	5,000	4,886
Balance at Jun. 30, 2021	6,572,080		66	760	7	0	(513,377)	6,956,520	36,124	6,480,100	91,980
Balance at Jun. 30, 2021		4,693
Common Stock
Issued/(converted)	3,665							3,665		3,665
Repurchased	(420,459)			(28)				(420,431)		(420,459)
Restricted share-based compensation expense	3,481							3,481		3,481
Dividends paid and accrued	(16,469)						(16,469)			(16,469)
Stock option expense	14,582							14,582		14,582
Distributions to noncontrolling interests	(127)										(127)
Purchase of noncontrolling interest / Purchase of ownership interests by minority members	1,093										1,093
Comprehensive income:
Net income to UHS / noncontrolling interests	219,182							218,351		218,351	831
Net income attributable to redeemable noncontrolling interest		193
Foreign currency translation adjustments, net of income tax	(9,230)								(9,230)	(9,230)
Subtotal - comprehensive income	209,952							218,351	(9,230)	209,121	831
Subtotal attributable to redeemable noncontrolling interest		193
Balance at Sep. 30, 2021	6,367,798		$ 66	$ 732	$ 7	$ 0	$ (529,846)	$ 6,776,168	$ 26,894	$ 6,274,021	$ 93,777
Balance at Sep. 30, 2021	$ 5,000	$ 4,886