Derivative Instruments and Fair Value Accounting Derivative Instruments (Details) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ 1,967.9	$ 2,016.0	$ 2,466.1	$ 2,378.9
Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, 2018 Secured Railcar Equipment Notes [Domain]
Derivative [Line Items]
Derivative, Notional Amount		$ 249.3
Derivative, Average Fixed Interest Rate	[1]	4.41%
Derivative Liability		$ 0.0
Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, TRIP Holdings Warehouse Loan [Member]
Derivative [Line Items]
Derivative, Notional Amount		$ 788.5
Derivative, Average Fixed Interest Rate	[1]	3.60%
Derivative Liability		$ 0.0
Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, TRIP Master Funding Secured Railcar Equipment Notes [Member]
Derivative [Line Items]
Derivative, Notional Amount		$ 34.8
Derivative, Average Fixed Interest Rate	[1]	2.62%
Derivative Liability		$ 0.0
Designated as Hedging Instrument [Member] | Interest Rate Cap [Member]
Derivative [Line Items]
Derivative, Notional Amount		$ 169.3
Derivative, Cap Interest Rate	[1]	3.00%
Derivative Liability		$ 0.0
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		$ 481.3
Derivative, Average Fixed Interest Rate		2.66%
Derivative Liability		$ (33.4)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, 2018 Secured Railcar Equipment Notes [Domain]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		0.8
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, TRIP Holdings Warehouse Loan [Member]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		1.1
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, TRIP Master Funding Secured Railcar Equipment Notes [Member]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		0.0
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Designated as Hedging Instrument [Member] | Interest Rate Cap [Member]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		(0.5)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		32.9
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, 2018 Secured Railcar Equipment Notes [Domain]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		0.0
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, TRIP Holdings Warehouse Loan [Member]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		1.5
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap, Expired, TRIP Master Funding Secured Railcar Equipment Notes [Member]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		0.1
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member] | Designated as Hedging Instrument [Member] | Interest Rate Cap [Member]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		0.0
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ 0.0

[1] (Mark One)