Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 771,312	$ 747,171	$ 750,698
Other comprehensive income (loss):
Unrealized derivative gains on cash flow hedges	6,679	1,438	4,970
Amortization of terminated hedge	0	(167)	(336)
Minimum pension liability	4,070	13,356	2,177
Unrealized loss on marketable security	(2,169)	(2,229)	0
Foreign currency translation adjustment	26,678	(10,038)	(1,728)
Other comprehensive income before tax	35,258	2,360	5,083
Income tax expense related to items of other comprehensive income	2,664	4,648	2,980
Total other comprehensive income (loss), net of tax	32,594	(2,288)	2,103
Comprehensive income	803,906	744,883	752,801
Less: Comprehensive income attributable to noncontrolling interests	19,009	44,762	70,170
Comprehensive income attributable to UHS	$ 784,897	$ 700,121	$ 682,631