Derivative Instruments and Fair Value Accounting Derivative Instruments (Details) - USD ($) $ in Millions		Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ 2,093.6	$ 2,160.4	$ 2,466.1	$ 2,378.9	$ 2,459.3	$ 2,529.6	$ 2,565.1	$ 2,562.0
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		$ 494.6
Derivative, Average Fixed Interest Rate		2.66%
Derivative Liability		$ (50.0)
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		0.9
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		1.6
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		0.1
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		49.5
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		2.1
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)