Note 8. Debt Components and Fair Value of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Debt and Lease Obligation	$ 448.2	$ 522.8
Non-Recourse Debt	4,568.8	4,359.1
Debt:	5,017.0	4,881.9
Long-term Debt, Fair Value	5,254.8	5,064.6
Corporate Segment [Member]
Debt Instrument [Line Items]
Long-term Debt, Net of Unamortized Discount, Gross of Unamortized Debt Issuance Costs	449.8	524.8
Unamortized Debt Issuance Expense	1.6	2.0
Long-term Debt, Fair Value	470.3	536.7
Wholly Owned Subsidiaries [Member]
Debt Instrument [Line Items]
Non-Recourse Debt	3,340.5	3,080.7
Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense	24.0	23.9
Non-Recourse Debt, Gross of Issuance Cost, Net of Discount	3,364.5	3,104.6
Non-Recourse Debt	3,340.5	3,080.7
Long-term Debt, Fair Value	3,450.9	3,169.5
Partially-Owned Subsidiaries [Member]
Debt Instrument [Line Items]
Non-Recourse Debt	1,228.3	1,278.4
Partially-Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense	9.2	10.9
Non-Recourse Debt, Gross	1,237.5	1,289.3
Non-Recourse Debt	1,228.3	1,278.4
Long-term Debt, Fair Value	1,333.6	1,358.4
2006 Secured Railcar Equipment Notes [Member] \| Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross	0.0	109.3
Long-term Debt, Fair Value	0.0	114.0
2009 Secured Railcar Equipment Notes [Member] \| Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross	142.3	147.8
Long-term Debt, Fair Value	170.0	168.7
2010 Secured Railcar Equipment Notes [Member] \| Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross	235.9	248.5
Long-term Debt, Fair Value	248.5	264.3
2018 Secured Railcar Equipment Notes [Domain] \| Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross of Issuance Cost, Net of Discount	434.7	452.1
Debt Instrument, Unamortized Discount	0.2	0.2
Long-term Debt, Fair Value	449.3	466.2
TRIHC 2018 Secured Railcar Equipment Notes [Member] \| Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross of Issuance Cost, Net of Discount	0.0	265.4
Debt Instrument, Unamortized Discount	0.0	1.4
Long-term Debt, Fair Value	0.0	270.9
2019 Secured Railcar Equipment Notes [Domain] [Domain] \| Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross of Issuance Cost, Net of Discount	860.5	901.0
Debt Instrument, Unamortized Discount	0.3	0.4
Long-term Debt, Fair Value	890.8	904.9
TRL 2012 Secured Railcar Equipment Notes - RIV 2013 [Member] \| Partially-Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross	352.5	371.4
Long-term Debt, Fair Value	373.9	374.4
TRIP Master Funding Secured Railcar Equipment Notes [Member] \| Partially-Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross	885.0	917.9
Long-term Debt, Fair Value	959.7	984.0
2020 Secured Railcar Equipment Notes [Domain] \| Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross of Issuance Cost, Net of Discount	369.0	0.0
Debt Instrument, Unamortized Discount	0.1	0.0
Long-term Debt, Fair Value	370.2	0.0
Senior Notes [Member] \| Corporate Segment [Member]
Debt Instrument [Line Items]
Long-term Debt, Net of Unamortized Discount, Gross of Unamortized Debt Issuance Costs	399.8	399.8
Debt Instrument, Unamortized Discount	0.2	0.2
Long-term Debt, Fair Value	420.3	411.7
Promissory Notes [Member] \| 2017 Secured Railcar Equipment Notes [Member] [Domain] \| Wholly Owned Subsidiaries [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross of Issuance Cost, Net of Discount	802.7	627.1
Debt Instrument, Unamortized Discount	10.1	0.0
Long-term Debt, Fair Value	802.7	627.1
Secured Debt [Member] \| 2019 Secured Railcar Equipment Notes [Domain] [Domain] \| Wholly Owned Subsidiaries [Member]
Debt Instrument [Line Items]
Non-Recourse Debt, Gross	491.1
Revolving Credit Facility [Member] \| Line of Credit [Member] \| Corporate Segment [Member]
Debt Instrument [Line Items]
Long-term Debt, Net of Unamortized Discount, Gross of Unamortized Debt Issuance Costs	50.0	125.0
Long-term Debt, Fair Value	50.0	125.0
Revolving Credit Facility [Member] \| Line of Credit [Member] \| TILC Warehouse Facility [Member] \| TILC [Member] \| Railcar Leasing and Management Services Group [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	519.4	353.4
Long-term Debt, Fair Value	$ 519.4	$ 353.4

Long-term Debt, Net of Unamortized Discount, Gross of Unamortized Debt Issuance Costs

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Non-Recourse Debt, Gross

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Recourse And Non-Recourse Debt And Capital Lease Obligations

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Amount of short-term and long-term debt and lease obligation.

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Amount, after accumulated amortization, of debt discount.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Amount of debt for which creditor does not have general recourse to the debtor but rather has recourse only to the property used for collateral in the transaction or other specific property.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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