Note 3. Derivative Instruments and Fair Value Measurements Derivatives - Effect on Interest Expense (Details) - Interest Expense [Member] - Designated as Hedging Instrument [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Interest Rate Swap, Expired, 2006 Secured Railcar Equipment Notes [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		$ (0.1)	[1]	$ (0.2)	$ (0.2)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	[2]	0.0
Interest Rate Swap, Expired, 2018 Secured Railcar Equipment Notes [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0.2		0.2	0.1
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	[2]	(0.2)
Interest Rate Swap, Expired, TRIP Holdings Warehouse Loan [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		2.0		2.0	2.2
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	[2]	(1.8)
Interest Rate Swap, Expired, TRIP Master Funding Secured Railcar Equipment Notes [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0.2		0.2	0.2
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	[2]	(0.1)
Interest Rate Cap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		(0.1)		(0.1)	0.1
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	[2]	0.1
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		11.0		$ 3.1	$ 0.3
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	[2]	$ (11.0)

[1] Upon settlement of the debt in March 2020, the remaining balance of $0.1 million in AOCL was recognized through interest expense. See Note 8 for additional information on the debt redemption.

[2] Based on the fair value of open hedges as of December 31, 2020