Note 4. Segment Information Segment Information (Details)		3 Months Ended	12 Months Ended
		Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) segment		Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment			3
External Revenue			$ 1,999,400,000		$ 3,005,100,000	$ 2,509,100,000
Revenues:			1,999,400,000		3,005,100,000	2,509,100,000
Total operating profit (loss)			(124,500,000)		416,300,000	315,100,000
Restructuring Charges			(11,000,000.0)		(14,700,000)	0
Other Nonoperating Expense			2,500,000		1,100,000
Provision (benefit) for income taxes:			(268,400,000)		61,500,000	42,600,000
Income (loss) from discontinued operations, net of provision (benefit) for income taxes of $(0.1), $(1.0), $30.7			(100,000)		(3,100,000)	54,100,000
Net income (loss)			(226,200,000)		136,100,000	163,100,000
Depreciation and amortization			266,000,000.0		283,600,000	251,900,000
Payments to Acquire Productive Assets			704,500,000		1,219,200,000	985,600,000
Total assets			8,701,800,000		8,701,400,000
Asset Impairment Charges		$ (369,400,000)	$ (396,400,000)		0	0
Concentration Risk, Percentage			14.00%
Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
External Revenue			$ 801,500,000		1,116,300,000	842,000,000.0
Revenues:			802,300,000		1,117,200,000	842,800,000
Total operating profit (loss)			353,700,000		406,600,000	351,100,000
Restructuring Charges			(1,400,000)		(200,000)
Rail Products Group [Member]
Segment Reporting Information [Line Items]
External Revenue			948,200,000		1,635,300,000	1,409,200,000
Total operating profit (loss)			36,300,000		277,600,000	167,600,000
Restructuring Charges			(1,300,000)		(700,000)
Other Segments [Member]
Segment Reporting Information [Line Items]
External Revenue			249,700,000		253,500,000	257,900,000
Total operating profit (loss)			28,200,000		19,900,000	40,200,000
Restructuring Charges			(400,000)		(11,400,000)
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Total operating profit (loss)			(97,700,000)		(108,000,000.0)	(149,100,000)
Restructuring Charges			(7,900,000)		(2,400,000)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total operating profit (loss)			418,200,000		704,100,000	558,900,000
Total assets			8,710,100,000		9,228,100,000
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Revenues:			802,300,000		1,117,200,000	842,800,000
Total operating profit (loss)	[1]		353,700,000		406,600,000	351,100,000
Depreciation and amortization			214,700,000	[2],[3]	232,200,000	196,600,000
Payments to Acquire Productive Assets			602,200,000		1,122,200,000	948,300,000
Total assets			7,652,100,000		8,012,600,000
Operating Segments [Member] | Rail Products Group [Member]
Segment Reporting Information [Line Items]
Revenues:			1,609,500,000		2,974,800,000	2,412,900,000
Depreciation and amortization			35,100,000		34,100,000	35,600,000
Payments to Acquire Productive Assets			78,500,000		85,600,000	18,700,000
Total assets			858,600,000		1,019,800,000
Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues:			251,200,000		261,000,000.0	270,600,000
Depreciation and amortization			8,000,000.0		8,300,000	9,800,000
Payments to Acquire Productive Assets			6,300,000		9,100,000	14,600,000
Total assets			199,400,000		195,700,000
Operating Segments [Member] | Corporate Segment [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization			8,200,000		9,000,000.0	9,900,000
Payments to Acquire Productive Assets			17,500,000		2,300,000	4,000,000.0
Total assets			812,000,000.0		378,100,000
Intersegment Eliminations [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues			800,000		900,000	800,000
Intersegment Eliminations [Member] | Rail Products Group [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues			661,300,000		1,339,500,000	1,003,700,000
Intersegment Eliminations [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues			1,500,000		7,500,000	12,700,000
MEXICO
Segment Reporting Information [Line Items]
Total assets			126,900,000		136,000,000.0
Long-Lived Assets			111,900,000		112,200,000
Consolidated Subsidiaries, Leasing [Member]
Segment Reporting Information [Line Items]
Total operating profit (loss)			(35,200,000)		(164,700,000)	(95,100,000)
Consolidated Subsidiaries, Leasing [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues			(652,900,000)		(1,331,100,000)	(990,300,000)
Revenues:			(652,900,000)		(1,331,100,000)	(990,300,000)
Depreciation and amortization			0		0	0
Payments to Acquire Productive Assets			0		0	0
Total assets	[4]		(820,300,000)		(903,800,000)
Consolidated Subsidiaries, Excluding Leasing [Member]
Segment Reporting Information [Line Items]
Total operating profit (loss)			(2,400,000)		(400,000)	400,000
Consolidated Subsidiaries, Excluding Leasing [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues			(10,700,000)		(16,800,000)	(26,900,000)
Revenues:			(10,700,000)		(16,800,000)	(26,900,000)
Depreciation and amortization			0		0	0
Payments to Acquire Productive Assets			0		0	$ 0
Total assets			$ 0		$ (1,000,000.0)

[1] Operating profit includes: depreciation; maintenance and compliance; rent; and selling, engineering, and administrative expenses. Amortization of deferred profit on railcars sold from the Rail Products Group to the Leasing Group is included in the operating profits of the Leasing Group, resulting in the recognition of depreciation expense based on our original manufacturing cost of the railcars. Interest expense is not a component of operating profit and includes the effect of hedges.

[2] As a result of the impairment of long-lived assets related to our small cube covered hopper railcars recorded in the second quarter of 2020, our quarterly depreciation expense beginning in the third quarter of 2020 has decreased by approximately $3.5 million, for a total reduction of $7.0 million for the year ended December 31, 2020

[3] Effective January 1, 2020, we revised the estimated useful lives and salvage values of certain railcar types in our lease fleet. This change in estimate resulted in a decrease in depreciation expense in the year ended December 31, 2020 of approximately $30.8 million. This decrease was partially offset by higher depreciation associated with growth in the lease fleet. See Note 1 for further information.

[4] Net deferred profit on railcars sold to the Leasing Group consists of intersegment profit that is eliminated in consolidation. Net deferred profit and the related deferred tax impact are included as adjustments to the property, plant, and equipment, net and deferred income taxes line items, respectively, in the Eliminations – Lease Subsidiary column above to reflect the net book value of the railcars purchased by the Leasing Group from the Rail Products Group based on manufacturing cost. See Note 5 and Note 8 for a further discussion regarding our investment in our partially-owned leasing subsidiaries and the related indebtedness.