Document and Entity Information Document - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 12, 2021	Jun. 30, 2020
Cover Page [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	1-6903
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	75-0225040
Entity Address, Address Line One	14221 N. Dallas Parkway, Suite 1100
Entity Address, City or Town	Dallas,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75254-2957
City Area Code	214
Local Phone Number	631-4420
Entity Registrant Name	TRINITY INDUSTRIES INC
Entity Central Index Key	0000099780
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Title of 12(b) Security	Common Stock
Trading Symbol	TRN
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
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Public Float			$ 1,934.5
Entity Common Stock, Shares Outstanding		110,972,157