Consolidated Statements of Changes in Equity and Income - USD ($) $ in Thousands	Total	Total Stockholders’ Equity	Common Stock	Capital in Excess of Par	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interests
Beginning balance (in shares) at Dec. 31, 2020			134,850,000
Beginning balance at Dec. 31, 2020	$ 1,252,973	$ 1,060,480	$ 135	$ 509,128	$ 553,244	$ (2,027)	$ 192,493
Increase (Decrease) in Stockholders' Equity
Net income attributable to Select Medical Holdings Corporation	402,225	402,225			402,225
Net income attributable to non-controlling interests	47,571	0					47,571
Cash dividends declared for common stockholders	(50,600)	(50,600)			(50,600)
Issuance of restricted stock (in shares)			1,363,000
Issuance of restricted stock	0	0	$ 1	(1)
Forfeitures of unvested restricted stock (in shares)			(18,000)
Forfeitures of unvested restricted stock	0	0	$ 0	0
Vesting of restricted stock	28,798	28,798		28,798
Repurchase of common shares (in shares)			(2,311,000)
Repurchase of common shares	(79,476)	(79,476)	$ (2)	(33,322)	(46,152)
Issuance of non-controlling interests	21,186	3,646		3,646			17,540
Non-controlling interests acquired in business combination, measurement period adjustment	11,153	0					11,153
Distributions to and purchases of non-controlling interests	(72,158)	(19,197)		(3,757)	(15,440)		(52,961)
Redemption value adjustment on non-controlling interests	(250,083)	(250,083)			(250,083)
Other comprehensive income	14,309	14,309				14,309
Other	4	(121)		(178)	57		125
Ending balance (in shares) at Dec. 31, 2021			133,884,000
Ending 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	158,994	158,994			158,994
Net income attributable to non-controlling interests	31,460	0					31,460
Cash dividends declared for common stockholders	(64,589)	(64,589)			(64,589)
Issuance of restricted stock (in shares)			1,642,000
Issuance of restricted stock	0	0	$ 1	(1)
Forfeitures of unvested restricted stock (in shares)			(98,000)
Forfeitures of unvested restricted stock	64	64	$ 0	0	64
Vesting of restricted stock	35,550	35,550		35,550
Repurchase of common shares (in shares)			(8,255,000)
Repurchase of common shares	(195,528)	(195,528)	$ (8)	(87,838)	(107,682)
Issuance of non-controlling interests	10,170	665		665			9,505
Non-controlling interests acquired in business combination, measurement period adjustment	12,463	0					12,463
Distributions to and purchases of non-controlling interests	(37,664)	(2,957)		(507)	(2,450)		(34,707)
Redemption value adjustment on non-controlling interests	3,385	3,385			3,385
Other comprehensive income	76,320	76,320				76,320
Other	$ 37	37			37
Ending balance (in shares) at Dec. 31, 2022	127,173,871		127,173,000
Ending 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	243,491	243,491			243,491
Net income attributable to non-controlling interests	48,153	0					48,153
Cash dividends declared for common stockholders	(63,904)	(63,904)			(63,904)
Issuance of restricted stock (in shares)			1,651,000
Issuance of restricted stock	0	0	$ 1	(1)
Forfeitures of unvested restricted stock (in shares)			(12,000)
Forfeitures of unvested restricted stock	12	12	$ 0	0	12
Vesting of restricted stock	43,619	43,619		43,619
Repurchase of common shares (in shares)			(443,000)
Repurchase of common shares	(12,759)	(12,759)	$ 0	(5,184)	(7,575)
Issuance of non-controlling interests	23,051	1,870		1,870			21,181
Non-controlling interests acquired in business combination, measurement period adjustment	9,007	0					9,007
Distributions to and purchases of non-controlling interests	(55,314)	(1,745)		927	(2,672)		(53,569)
Redemption value adjustment on non-controlling interests	1,527	1,527			1,527
Other comprehensive income	(45,695)	(45,695)				(45,695)
Other	$ (34)	(34)		(1)	(33)
Ending balance (in shares) at Dec. 31, 2023	128,369,492		128,369,000
Ending balance at Dec. 31, 2023	$ 1,547,718	$ 1,288,304	$ 128	$ 493,413	$ 751,856	$ 42,907	$ 259,414