Note 1. Summary of Significant Accounting Policies Change in Depreciable Lives (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2021	[1]	Sep. 30, 2021	[1]	Jun. 30, 2021	[1]	Mar. 31, 2021	[1]	Dec. 31, 2020	[1]	Sep. 30, 2020	[1]	Jun. 30, 2020	[1]	Mar. 31, 2020	[1]	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in Accounting Estimate [Line Items]
Depreciation and amortization																	$ 265.7	$ 258.5	$ 276.5
Basic net income (loss) attributable to Trinity Industries, Inc.	$ 1.39		$ 0.33		$ 0.12		$ 0.03		$ (1.13)		$ 0.21		$ (1.76)		$ 1.36		$ 1.79	$ (1.27)	$ 1.09
Diluted net income (loss) attributable to Trinity Industries, Inc.	$ 1.37		$ 0.33		$ 0.12		$ 0.03		$ (1.13)		$ 0.21		$ (1.76)		$ 1.33		$ 1.75	$ (1.27)	$ 1.07
Service Life [Member]
Change in Accounting Estimate [Line Items]
Depreciation and amortization																	$ 30.8	$ 30.8
Depreciation, Amortization and Accretion, Net																	$ 23.7	$ 23.7
Basic net income (loss) attributable to Trinity Industries, Inc.																	$ 0.23	$ 0.20
Diluted net income (loss) attributable to Trinity Industries, Inc.																	$ 0.23	$ 0.20

[1] The sum of the quarters may not necessarily be equal to the full year net income per common share amount.