v3.25.2
Cover - shares
 6 Months Ended
Jun. 30, 2025
Jul. 31, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2025  
Document Transition Report false  
Entity File Number 001-34465  
Entity Registrant Name SELECT MEDICAL HOLDINGS CORP  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 20-1764048  
Entity Address, Address Line One 4714 Gettysburg Road  
Entity Address, Address Line Two P.O. Box 2034  
Entity Address, City or Town Mechanicsburg  
Entity Address, State or Province PA  
Entity Address, Postal Zip Code 17055  
City Area Code 717  
Local Phone Number 972-1100  
Title of 12(b) Security Common Stock, par value $0.001 per share  
Trading Symbol SEM  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   123,989,261
Entity Central Index Key 0001320414  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2