Condensed Consolidated Statements of Changes in Equity and Income (unaudited) - USD ($) $ in Thousands	Total	Total Stockholders’ Equity	Common Stock	Capital in Excess of Par	Retained Earnings	Accumulated Other Comprehensive Income	Non-controlling Interests
Beginning balance (in shares) at Dec. 31, 2021			133,884,000
Beginning balance at Dec. 31, 2021	$ 1,325,902	$ 1,109,981	$ 134	$ 504,314	$ 593,251	$ 12,282	$ 215,921
Increase (Decrease) in Stockholders' Equity
Net income attributable to Select Medical Holdings Corporation	49,117	49,117			49,117
Net income attributable to non-controlling interests	4,891	0					4,891
Cash dividends declared for common stockholders ($0.125 per share)	(16,691)	(16,691)			(16,691)
Issuance of restricted stock (in shares)			13,000
Issuance of restricted stock	0	0	$ 0	0
Vesting of restricted stock	8,288	8,288		8,288
Repurchase of common shares (in shares)			(2,128,000)
Repurchase of common shares	(51,676)	(51,676)	$ (2)	(23,459)	(28,215)
Issuance of non-controlling interests	5,229	651		651			4,578
Non-controlling interests acquired in business combination, measurement period adjustment	12,463	0					12,463
Distributions to and purchases of non-controlling interests	(9,097)	0					(9,097)
Redemption value adjustment on non-controlling interests	(1,381)	(1,381)			(1,381)
Other comprehensive income (loss)	39,853	39,853				39,853
Other	(2)	(2)			(2)
Ending balance (in shares) at Mar. 31, 2022			131,769,000
Ending balance at Mar. 31, 2022	1,366,896	1,138,140	$ 132	489,794	596,079	52,135	228,756
Beginning balance (in shares) at Dec. 31, 2021			133,884,000
Beginning balance at Dec. 31, 2021	1,325,902	1,109,981	$ 134	504,314	593,251	12,282	215,921
Increase (Decrease) in Stockholders' Equity
Net income attributable to Select Medical Holdings Corporation	104,324
Ending balance (in shares) at Jun. 30, 2022			126,491,000
Ending balance at Jun. 30, 2022	1,303,701	1,071,413	$ 126	441,769	565,556	63,962	232,288
Beginning balance (in shares) at Mar. 31, 2022			131,769,000
Beginning balance at Mar. 31, 2022	1,366,896	1,138,140	$ 132	489,794	596,079	52,135	228,756
Increase (Decrease) in Stockholders' Equity
Net income attributable to Select Medical Holdings Corporation	55,207	55,207			55,207
Net income attributable to non-controlling interests	9,155	0					9,155
Cash dividends declared for common stockholders ($0.125 per share)	(16,108)	(16,108)			(16,108)
Issuance of restricted stock (in shares)			211,000
Issuance of restricted stock	0	0	$ 0	0
Forfeitures of unvested restricted stock (in shares)			(6,000)
Forfeitures of unvested restricted stock	3	3	$ 0	0	3
Vesting of restricted stock	8,406	8,406		8,406
Repurchase of common shares (in shares)			(5,483,000)
Repurchase of common shares	(126,947)	(126,947)	$ (6)	(56,965)	(69,976)
Issuance of non-controlling interests	1,725	0		0			1,725
Distributions to and purchases of non-controlling interests	(6,814)	534		534			(7,348)
Redemption value adjustment on non-controlling interests	355	355			355
Other comprehensive income (loss)	11,827	11,827				11,827
Other	(4)	(4)			(4)		0
Ending balance (in shares) at Jun. 30, 2022			126,491,000
Ending balance at Jun. 30, 2022	$ 1,303,701	1,071,413	$ 126	441,769	565,556	63,962	232,288
Beginning balance (in shares) at Dec. 31, 2022	127,173,871		127,173,000
Beginning balance at Dec. 31, 2022	$ 1,356,564	1,121,922	$ 127	452,183	581,010	88,602	234,642
Increase (Decrease) in Stockholders' Equity
Net income attributable to Select Medical Holdings Corporation	70,805	70,805			70,805
Net income attributable to non-controlling interests	12,811	0					12,811
Cash dividends declared for common stockholders ($0.125 per share)	(15,897)	(15,897)			(15,897)
Issuance of restricted stock (in shares)			3,000
Issuance of restricted stock	0	0	$ 0	0
Vesting of restricted stock	10,003	10,003		10,003
Issuance of non-controlling interests	2,731	0					2,731
Non-controlling interests acquired in business combination, measurement period adjustment	3,877	0					3,877
Distributions to and purchases of non-controlling interests	(6,069)	0					(6,069)
Redemption value adjustment on non-controlling interests	(436)	(436)			(436)
Other comprehensive income (loss)	(15,948)	(15,948)				(15,948)
Other	0	0		(1)	1
Ending balance (in shares) at Mar. 31, 2023			127,176,000
Ending balance at Mar. 31, 2023	$ 1,418,441	1,170,449	$ 127	462,185	635,483	72,654	247,992
Beginning balance (in shares) at Dec. 31, 2022	127,173,871		127,173,000
Beginning balance at Dec. 31, 2022	$ 1,356,564	1,121,922	$ 127	452,183	581,010	88,602	234,642
Increase (Decrease) in Stockholders' Equity
Net income attributable to Select Medical Holdings Corporation	$ 149,042
Ending balance (in shares) at Jun. 30, 2023	127,387,869		127,388,000
Ending balance at Jun. 30, 2023	$ 1,501,579	1,246,038	$ 127	473,942	696,922	75,047	255,541
Beginning balance (in shares) at Mar. 31, 2023			127,176,000
Beginning balance at Mar. 31, 2023	1,418,441	1,170,449	$ 127	462,185	635,483	72,654	247,992
Increase (Decrease) in Stockholders' Equity
Net income attributable to Select Medical Holdings Corporation	78,237	78,237			78,237
Net income attributable to non-controlling interests	11,539	0					11,539
Cash dividends declared for common stockholders ($0.125 per share)	(15,924)	(15,924)			(15,924)
Issuance of restricted stock (in shares)			261,000
Issuance of restricted stock	0	0	$ 0	0
Vesting of restricted stock	10,326	10,326		10,326
Repurchase of common shares (in shares)			(49,000)
Repurchase of common shares	(1,506)	(1,506)	$ 0	(634)	(872)
Issuance of non-controlling interests	12,081	1,870		1,870			10,211
Distributions to and purchases of non-controlling interests	(14,006)	195		195			(14,201)
Redemption value adjustment on non-controlling interests	(2)	(2)			(2)
Other comprehensive income (loss)	$ 2,393	2,393				2,393
Ending balance (in shares) at Jun. 30, 2023	127,387,869		127,388,000
Ending balance at Jun. 30, 2023	$ 1,501,579	$ 1,246,038	$ 127	$ 473,942	$ 696,922	$ 75,047	$ 255,541