v3.26.1
Debt - Components of debt (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Debt Instrument [Line Items]    
Debt: $ 5,226.5 $ 5,442.5
Recourse    
Debt Instrument [Line Items]    
Debt: 598.8 598.5
Nonrecourse    
Debt Instrument [Line Items]    
Debt: 4,627.7 4,844.0
Level 2    
Debt Instrument [Line Items]    
Long-term Debt, Fair Value 613.3 623.9
Level 3    
Debt Instrument [Line Items]    
Long-term Debt, Fair Value 3,054.5 3,303.6
Corporate Segment [Member]    
Debt Instrument [Line Items]    
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 602.5 603.1
Less: unamortized debt issuance costs 3.7 4.6
TRL-2025 Series 2026-1 Class A Green Secured Railcar Equipment Notes [Member] | Corporate Segment [Member]    
Debt Instrument [Line Items]    
Payments of Debt Issuance Costs 5.4  
7.75% Senior Notes Due 2028 | Senior Notes due 2028 | Corporate Segment [Member]    
Debt Instrument [Line Items]    
Senior Notes 602.5 603.1
Debt Instrument, Unamortized Premium 2.5 3.1
Wholly Owned Subsidiaries [Member] | Nonrecourse    
Debt Instrument [Line Items]    
Debt: 4,627.7 4,573.4
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 4,650.5 4,594.3
Less: unamortized debt issuance costs 22.8 20.9
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member] | Nonrecourse    
Debt Instrument [Line Items]    
Debt: 4,627.7 4,573.4
Wholly Owned Subsidiaries [Member] | Secured Debt [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Unamortized Discount 0.4 0.3
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 3,073.4 3,036.3
Wholly Owned Subsidiaries [Member] | TRL-2023 Term Loan | Line of Credit [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Long-term Line of Credit 1,017.5 1,031.9
Debt Instrument, Unamortized Discount 0.6 0.6
Wholly Owned Subsidiaries [Member] | Other Equipment Financing | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Secured Debt, Other 46.4 47.6
Partially-Owned Subsidiaries [Member] | Nonrecourse    
Debt Instrument [Line Items]    
Debt: 0.0 270.6
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Less: unamortized debt issuance costs 0.0 0.7
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member] | Nonrecourse    
Debt Instrument [Line Items]    
Debt: 0.0 270.6
Partially-Owned Subsidiaries [Member] | Secured Debt [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Unamortized Discount 0.0 0.0
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 0.0 271.3
Revolving Credit Facility [Member] | Line of Credit [Member] | Corporate Segment [Member]    
Debt Instrument [Line Items]    
Long-term Line of Credit 0.0 0.0
Payments of Debt Issuance Costs 1.3  
Revolving Credit Facility [Member] | TILC [Member] | TILC Warehouse Facility [Member] | Line of Credit [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Long-term Line of Credit $ 513.2 $ 478.5