Condensed Consolidated Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue	$ 1,534,221	$ 1,423,869	$ 4,644,704	$ 4,071,219
Costs and expenses:
Cost of services, exclusive of depreciation and amortization	1,297,682	1,180,951	3,882,579	3,463,778
General and administrative	37,885	35,516	109,025	102,808
Depreciation and amortization	50,128	50,110	150,702	154,133
Total costs and expenses	1,385,695	1,266,577	4,142,306	3,720,719
Other operating income	1,729	(1,160)	133,837	53,828
Income from operations	150,255	156,132	636,235	404,328
Other income and expense:
Equity in earnings of unconsolidated subsidiaries	11,452	8,765	33,180	19,677
Gain on sale of businesses	0	5,143	0	12,690
Interest income	0	0	4,749	0
Interest expense	(33,825)	(34,026)	(102,115)	(117,499)
Income before income taxes	127,882	136,014	572,049	319,196
Income tax expense	27,665	31,557	138,410	76,805
Net income	100,217	104,457	433,639	242,391
Less: Net income attributable to non-controlling interests	23,289	27,511	81,271	60,670
Net income attributable to Select Medical Holdings Corporation	$ 76,928	$ 76,946	$ 352,368	$ 181,721
Earnings per common share (Note 13):
Basic (in dollars per share)	$ 0.57	$ 0.57	$ 2.61	$ 1.35
Diluted (in dollars per share)	$ 0.57	$ 0.57	$ 2.61	$ 1.35