Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2021	Nov. 03, 2021	Mar. 31, 2021
Cover [Abstract]
Document Type	10-K/A
Document Annual Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-32833
Entity Registrant Name	TransDigm Group Incorporated
Entity Central Index Key	0001260221
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	41-2101738
Entity Address, Address Line One	1301 East 9th Street,
Entity Address, Address Line Two	Suite 3000,
Entity Address, City or Town	Cleveland,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	44114
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 Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 32,940,645,808
Entity Common Stock, Shares Outstanding		55,248,901
Documents Incorporated by Reference	None