Railcar Leasing and Management Services Group (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Total revenues	$ 1,547.0	$ 1,542.2	$ 1,676.8	$ 1,626.7	$ 1,661.4	$ 1,562.8	$ 1,485.3	$ 1,460.5	$ 6,392.7	$ 6,170.0	$ 4,365.3
Operating profit:
Total operating profit	$ 358.0	$ 364.9	$ 382.9	$ 333.1	$ 276.5	$ 281.2	$ 302.0	$ 391.3	1,438.9	1,251.0	772.9
Selected expense information:
Depreciation									266.4	244.6	211.5
Interest:
Total interest expense									194.7	193.4	187.3
Operating Segments
Revenues:
Total revenues									7,978.1	7,228.0	5,366.6
Operating profit:
Total operating profit									1,852.0	1,502.7	982.8
Selected expense information:
Depreciation									258.7	237.3	207.1
Intercompany
Revenues:
Total revenues									1,585.4	1,058.0	1,001.3
Railcar Leasing and Management Services Group
Revenues:
Total revenues									1,091.6	1,106.4	645.4
Selected expense information:
Depreciation									142.3	130.0	129.0
Interest:
Total interest expense									138.8	153.3	153.5
Railcar Leasing and Management Services Group | Operating Segments
Revenues:
Total revenues									$ 1,104.8	$ 1,118.3	645.4
Percent Change, Revenues									(1.20%)	73.30%
Operating profit:
Total operating profit									$ 606.2	$ 516.3	$ 296.8
Percentage Change, Operating profit									17.40%	74.00%
Operating profit margin:
Total operating profit margin									54.90%	46.20%	46.00%
Selected expense information:
Depreciation									$ 142.3	$ 130.0	$ 129.0
Percent Change, Depreciation									9.50%	0.80%
Maintenance									$ 97.3	$ 78.9	71.5
Percent Change, Maintenance									23.30%	10.30%
Rent									$ 41.6	$ 52.9	53.3
Percent Change, Rent									(21.40%)	(0.80%)
Interest:
Total interest expense									$ 138.8	$ 153.3	157.3
Percent Change, Total interest expense									(9.50%)	(2.50%)
Railcar Leasing and Management Services Group | Operating Segments | Leasing and management
Revenues:
Total revenues									$ 699.9	$ 632.0	586.9
Percent Change, Revenues									10.70%	7.70%
Operating profit:
Total operating profit									$ 331.1	$ 287.9	$ 267.3
Percentage Change, Operating profit									15.00%	7.70%
Operating profit margin:
Total operating profit margin									47.30%	45.60%	45.50%
Railcar Leasing and Management Services Group | Operating Segments | Railcars owned one year or less at the time of sale
Revenues:
Total revenues									$ 404.9	$ 486.3	$ 58.5
Operating profit:
Total operating profit									109.0	136.1	9.1
Railcar Leasing and Management Services Group | Operating Segments | Railcars owned more than one year at the time of sale
Operating profit:
Total operating profit									166.1	92.3	20.4
Railcar Leasing and Management Services Group | Intercompany
Revenues:
Total revenues									13.2	11.9	0.0
Interest:
Total interest expense									$ 0.0	$ 0.0	$ 3.8