Condensed Consolidated Statements of Changes in Equity and Income (unaudited) - USD ($) $ in Thousands	Total	Select Medical Corporation	Common Stock	Common Stock Select Medical Corporation	Capital in Excess of Par	Capital in Excess of Par Select Medical Corporation	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit) Select Medical Corporation	Total Stockholders’ Equity	Total Stockholders’ Equity Select Medical Corporation	Non-controlling Interests	Non-controlling Interests Select Medical Corporation
Balance (in shares) at Dec. 31, 2017			134,115,000	0
Balance at Dec. 31, 2017	$ 932,604	$ 932,604	$ 134	$ 0	$ 463,499	$ 947,370	$ 359,735	$ (124,002)	$ 823,368	$ 823,368	$ 109,236	$ 109,236
Increase (Decrease) in Stockholders' Equity
Net income	33,739	33,739					33,739	33,739	33,739	33,739
Net income attributable to non-controlling interests	4,500	4,500									4,500	4,500
Issuance of restricted stock (in shares)			4,000
Issuance of restricted stock	0		$ 0		0
Forfeitures of unvested restricted stock (in shares)			(88,000)
Forfeitures of unvested restricted stock	0		$ 0		0
Vesting of restricted stock	4,717				4,717				4,717
Repurchase of common shares (in shares)			(7,000)
Repurchase of common shares	(122)		$ 0		(69)		(53)		(122)
Exercise of stock options (in shares)			80,000
Exercise of stock options	738		$ 0		738				738
Additional investment by Holdings		738				738				738
Dividends declared and paid to Holdings		(122)						(122)		(122)
Contribution related to restricted stock award issuances by Holdings		4,717				4,717				4,717
Issuance and exchange of non-controlling interests	74,341	74,341					74,341	74,341	74,341	74,341
Distributions to and purchases of non-controlling interests	(84,327)	(84,327)					(83,233)	(83,233)	(83,233)	(83,233)	(1,094)	(1,094)
Redemption adjustment on non-controlling interests	(1,051)	(1,051)					(1,051)	(1,051)	(1,051)	(1,051)
Other	138	138					103	103	103	103	35	35
Balance (in shares) at Mar. 31, 2018			134,104,000	0
Balance at Mar. 31, 2018	$ 965,277	$ 965,277	$ 134	$ 0	468,885	952,825	383,581	(100,225)	852,600	852,600	112,677	112,677
Balance (in shares) at Dec. 31, 2018	135,265,864	100	135,266,000	0
Balance at Dec. 31, 2018	$ 916,240	$ 916,240	$ 135	$ 0	482,556	970,156	320,351	(167,114)	803,042	803,042	113,198	113,198
Increase (Decrease) in Stockholders' Equity
Net income	40,834	40,834					40,834	40,834	40,834	40,834
Net income attributable to non-controlling interests	4,810	4,810									4,810	4,810
Issuance of restricted stock (in shares)			21,000
Issuance of restricted stock	0		$ 0		0
Forfeitures of unvested restricted stock (in shares)			(24,000)
Forfeitures of unvested restricted stock	0		$ 0		0
Vesting of restricted stock	5,488				5,488				5,488
Contribution related to restricted stock award issuances by Holdings		5,488				5,488				5,488
Issuance of non-controlling interests	6,837	6,837									6,837	6,837
Distributions to and purchases of non-controlling interests	(2,480)	(2,480)			259	259			259	259	(2,739)	(2,739)
Redemption adjustment on non-controlling interests	(47,470)	(47,470)					(47,470)	(47,470)	(47,470)	(47,470)
Other	$ 291	$ 291					(122)	(122)	(122)	(122)	413	413
Balance (in shares) at Mar. 31, 2019	135,262,866	100	135,263,000	0
Balance at Mar. 31, 2019	$ 924,550	$ 924,550	$ 135	$ 0	$ 488,303	$ 975,903	$ 313,593	$ (173,872)	$ 802,031	$ 802,031	$ 122,519	$ 122,519