Derivative Instruments and Fair Value Accounting Derivative Instruments (Details) - USD ($) $ in Millions		Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ 1,596.4	$ 1,657.9	$ 1,967.9	$ 2,016.0	$ 2,093.6	$ 2,160.4	$ 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 Cap [Member]
Derivative [Line Items]
Derivative, Notional Amount		$ 169.3
Derivative, Cap Interest Rate		3.00%
Derivative Liability		$ 0.0
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		$ 468.0
Derivative, Average Fixed Interest Rate	[1]	2.66%
Derivative Liability		$ (28.9)
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		0.7
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		0.7
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		(0.4)
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		28.5
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		1.0
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)