Segment Information - Financial information for segments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 973.6	$ 1,111.7	$ 2,756.4	$ 3,484.5
Operating Profit (Loss)	153.0	183.6	404.8	578.6
Intersegment
Segment Reporting Information [Line Items]
Total revenues	225.8	289.9	648.2	987.7
Intersegment | Eliminations – Other
Segment Reporting Information [Line Items]
Total revenues	(65.3)	(83.2)	(190.8)	(245.6)
Operating Profit (Loss)	(0.9)	(0.4)	(5.4)	1.2
Intersegment | Eliminations – Lease subsidiary
Segment Reporting Information [Line Items]
Total revenues	(160.5)	(206.7)	(457.4)	(742.1)
Operating Profit (Loss)	(13.6)	(27.7)	(56.1)	(139.1)
Total
Segment Reporting Information [Line Items]
Total revenues	1,199.4	1,401.6	3,404.6	4,472.2
Operating Profit (Loss)	209.0	247.3	581.1	811.5
Corporate
Segment Reporting Information [Line Items]
Operating Profit (Loss)	(41.5)	(35.6)	(114.8)	(95.0)
Rail Group
Segment Reporting Information [Line Items]
Total revenues	317.4	506.0	938.8	1,476.9
Rail Group | Intersegment
Segment Reporting Information [Line Items]
Total revenues	175.0	214.8	497.8	784.0
Rail Group | Total
Segment Reporting Information [Line Items]
Total revenues	492.4	720.8	1,436.6	2,260.9
Operating Profit (Loss)	50.6	103.6	138.3	349.6
Construction Products Group
Segment Reporting Information [Line Items]
Total revenues	130.1	136.3	381.7	399.6
Construction Products Group | Intersegment
Segment Reporting Information [Line Items]
Total revenues	1.8	3.5	4.6	10.9
Construction Products Group | Total
Segment Reporting Information [Line Items]
Total revenues	131.9	139.8	386.3	410.5
Operating Profit (Loss)	16.9	23.8	54.8	61.2
Inland Barge Group
Segment Reporting Information [Line Items]
Total revenues	28.1	98.9	124.3	328.0
Inland Barge Group | Intersegment
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Inland Barge Group | Total
Segment Reporting Information [Line Items]
Total revenues	28.1	98.9	124.3	328.0
Operating Profit (Loss)	(0.7)	11.7	6.2	38.6
Energy Equipment Group
Segment Reporting Information [Line Items]
Total revenues	220.6	194.6	660.6	626.2
Energy Equipment Group | Intersegment
Segment Reporting Information [Line Items]
Total revenues	25.6	47.1	79.5	129.5
Energy Equipment Group | Total
Segment Reporting Information [Line Items]
Total revenues	246.2	241.7	740.1	755.7
Operating Profit (Loss)	26.3	31.2	80.4	103.5
Railcar Leasing and Management Services Group
Segment Reporting Information [Line Items]
Total revenues	274.9	173.2	645.4	647.1
Railcar Leasing and Management Services Group | Intersegment
Segment Reporting Information [Line Items]
Total revenues	0.2	0.5	0.7	1.7
Railcar Leasing and Management Services Group | Total
Segment Reporting Information [Line Items]
Total revenues	275.1	173.7	646.1	648.8
Operating Profit (Loss)	120.6	80.5	316.4	272.4
All Other
Segment Reporting Information [Line Items]
Total revenues	2.5	2.7	5.6	6.7
All Other | Intersegment
Segment Reporting Information [Line Items]
Total revenues	23.2	24.0	65.6	61.6
All Other | Total
Segment Reporting Information [Line Items]
Total revenues	25.7	26.7	71.2	68.3
Operating Profit (Loss)	$ (4.7)	$ (3.5)	$ (15.0)	$ (13.8)