Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 55,926	$ 137,214
Other comprehensive income, net of tax:
Gain on interest rate cap cash flow hedge	39,814	8,151
Reclassification adjustment for losses (gains) included in net income	39	0
Net change, net of tax benefit (expense) of $(2,834) and $(13,284)	39,853	8,151
Comprehensive income	95,779	145,365
Less: Comprehensive income attributable to non-controlling interests	6,809	26,668
Comprehensive income attributable to Select Medical Holdings Corporation	$ 88,970	$ 118,697