v3.25.0.1
Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2024
Feb. 12, 2025
Jun. 30, 2024
Document and Entity Information [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2024    
Document Transition Report false    
Entity File Number 001-41721    
Entity Registrant Name Waystar Holding Corp.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 84-2886542    
Entity Address, Address Line One 1550 Digital Drive, #300    
Entity Address, City or Town Lehi    
Entity Address, State or Province UT    
Entity Address, Postal Zip Code 84043    
City Area Code 844    
Local Phone Number 492-9782    
Title of 12(b) Security Common Stock, par value $0.01 per share    
Trading Symbol WAY    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company true    
Entity Ex Transition Period false    
Entity Shell Company false    
Entity Public Float     $ 1,010,020,722
Entity Common Stock, Shares Outstanding   172,151,839  
Entity Central Index Key 0001990354    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2024    
Document Fiscal Period Focus FY    
ICFR Auditor Attestation Flag false    
Document Financial Statement Error Correction [Flag] false    
Amendment Flag false    
Auditor Name KPMG LLP    
Auditor Location Indianapolis, Indiana    
Auditor Firm ID 185