v3.26.3
DOCUMENT AND ENTITY INFORMATION - USD ($)
 12 Months Ended
Sep. 30, 2026
Oct. 30, 2026
Mar. 27, 2026
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Sep. 30, 2026    
Current Fiscal Year End Date --09-30    
Document Transition Report false    
Entity File Number 001-32833    
Entity Registrant Name TransDigm Group Incorporated    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 41-2101738    
Entity Address, Address Line One 1350 Euclid Avenue,    
Entity Address, Address Line Two Suite 1600,    
Entity Address, City or Town Cleveland,    
Entity Address, State or Province OH    
Entity Address, Postal Zip Code 44115    
City Area Code 216    
Local Phone Number 706-2960    
Title of 12(b) Security Common Stock, $0.01 par value    
Trading Symbol TDG    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Emerging Growth Company false    
Entity Small Business false    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction false    
Entity Shell Company false    
Entity Public Float     $ 63,280,488,578
Entity Common Stock, Shares Outstanding   54,589,836  
Documents Incorporated by Reference Certain sections of the registrant’s definitive Proxy Statement to be filed in connection with its 2027 Annual Meeting of Stockholders expected to be held on March 11, 2027 are incorporated by reference into Part III of this Annual Report on Form 10-K.    
Amendment Flag false    
Document Fiscal Year Focus 2026    
Document Fiscal Period Focus FY    
Entity Central Index Key 0001260221