Railcar Leasing and Management Services Group (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	$ 420.4		$ 573.0
Property, plant, and equipment, net	5,049.4		4,861.7
Net deferred profit on railcars sold to the Leasing Group	(587.4)		(562.7)
Property, plant, and equipment, net	4,462.0	[1]	4,299.0	[2]
Restricted cash	215.3	[1]	223.2
Debt:
Less: unamortized discount	(84.2)	[1]	(87.5)
Total debt	2,974.8	[1]	3,055.0
Net deferred tax liabilities	599.8		555.8
Recourse
Debt:
Recourse	496.2		545.6
Less: unamortized discount	(84.2)		(87.5)
Total debt	412.0		458.1
Non-Recourse
Debt:
Non-recourse	2,671.6		2,705.7
Less: non-recourse debt owned by Trinity	(108.8)		(108.8)
Partially-owned subsidiary
Consolidating Financial Information
Restricted cash	50.9	[1]	50.3
Leasing Group | Wholly-owned subsidiaries
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	4.2		5.7
Property, plant, and equipment, net	3,348.8		3,203.8	[2]
Equipment Pledged as Collateral for Specific Segment Debt	2,561.9
Net deferred profit on railcars sold to the Leasing Group	(408.1)		(381.8)	[2]
Property, plant, and equipment, net	2,940.7		2,822.0
Restricted cash	164.4		172.9
Debt:
Total debt	1,759.1		1,832.4
Net deferred tax liabilities	688.9		671.1
Leasing Group | Wholly-owned subsidiaries | Recourse
Debt:
Recourse	45.1		94.4
Less: unamortized discount	0		0
Total debt	45.1		94.4
Leasing Group | Wholly-owned subsidiaries | Non-Recourse
Debt:
Non-recourse	1,714.0		1,738.0
Less: non-recourse debt owned by Trinity	0		0
Leasing Group | Partially-owned subsidiary
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	0		0
Property, plant, and equipment, net			1,118.6	[2]
Net deferred profit on railcars sold to the Leasing Group	(179.3)		(180.9)	[2]
Property, plant, and equipment, net	930.8		937.7
Restricted cash	50.9		50.3
Debt:
Total debt	848.8		858.9
Net deferred tax liabilities	6.0		5.4
Leasing Group | Partially-owned subsidiary | Recourse
Debt:
Recourse	0		0
Less: unamortized discount	0		0
Total debt	0		0
Leasing Group | Partially-owned subsidiary | Non-Recourse
Debt:
Non-recourse	957.6		967.7
Less: non-recourse debt owned by Trinity	(108.8)		(108.8)
Manufacturing/Corporate
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	416.2		567.3
Property, plant, and equipment, net	590.5		539.3	[2]
Net deferred profit on railcars sold to the Leasing Group	0		0
Property, plant, and equipment, net	590.5		539.3
Restricted cash	0		0
Debt:
Total debt	366.9		363.7
Net deferred tax liabilities	(95.1)		(120.7)
Manufacturing/Corporate | Recourse
Debt:
Recourse	451.1		451.2
Less: unamortized discount			(87.5)
Total debt	366.9		363.7
Manufacturing/Corporate | Non-Recourse
Debt:
Non-recourse	0		0
Less: non-recourse debt owned by Trinity	0		0
Carrying Value
Debt:
Total debt	2,974.8		3,055.0	[2]
Carrying Value | Recourse
Debt:
Total debt	412.0		458.1	[2]
Carrying Value | Leasing Group | Non-Recourse
Debt:
Total debt	2,562.8		2,596.9	[2]
Carrying Value | Leasing Group | Wholly-owned subsidiaries | Recourse
Debt:
Total debt	45.1		94.4	[2]
Carrying Value | Manufacturing/Corporate | Recourse
Debt:
Less: unamortized discount	(84.2)		(87.5)	[2]
Total debt	$ 366.9		$ 363.7	[2]

[1] (unaudited)

[2] (as reported)