Railcar Leasing and Management Services Group (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Total revenues	$ 1,103.8	$ 1,111.7	$ 1,184.9	$ 1,187.9	$ 1,547.0	$ 1,542.2	$ 1,676.8	$ 1,626.7	$ 4,588.3	$ 6,392.7	$ 6,170.0
Operating profit:
Total operating profit	$ 163.6	$ 183.6	$ 191.6	$ 203.4	$ 358.0	$ 364.9	$ 382.9	$ 333.1	742.2	1,438.9	1,251.0
Selected expense information:
Depreciation									283.0	266.4	244.6
Interest:
Interest									181.9	194.7	193.4
Operating Segments
Revenues:
Total revenues									5,935.5	7,978.1	7,228.0
Operating profit:
Total operating profit									1,052.1	1,852.0	1,502.7
Selected expense information:
Depreciation									274.4	258.7	237.3
Railcar Leasing and Management Services Group
Revenues:
Total revenues									824.9	1,091.6	1,106.4
Selected expense information:
Depreciation									156.2	142.3	130.0
Railcar Leasing and Management Services Group | Operating Segments
Revenues:
Total revenues									$ 827.0	$ 1,104.8	1,118.3
Percent Change, Revenues									(25.10%)	(1.20%)
Operating profit:
Total operating profit									$ 360.1	$ 606.2	$ 516.3
Percentage Change, Operating profit									(40.60%)	17.40%
Operating profit margin:
Total operating profit margin									43.50%	54.90%	46.20%
Selected expense information:
Depreciation									$ 156.2	$ 142.3	$ 130.0
Percent Change, Depreciation									9.80%	9.50%
Maintenance and compliance									$ 104.3	$ 97.3	78.9
Percent Change, Maintenance									7.20%	23.30%
Rent									$ 39.3	$ 41.6	52.9
Percent Change, Rent									(5.50%)	(21.40%)
Interest:
Interest									$ 125.2	$ 138.8	153.3
Percent Change, Total interest expense									(9.80%)	(9.50%)
Railcar Leasing and Management Services Group | Operating Segments | Leasing and management
Revenues:
Total revenues									$ 700.9	$ 699.9	632.0
Percent Change, Revenues									0.10%	10.70%
Operating profit:
Total operating profit									$ 312.5	$ 331.1	$ 287.9
Percentage Change, Operating profit									(5.60%)	15.00%
Operating profit margin:
Total operating profit margin									44.60%	47.30%	45.60%
Railcar Leasing and Management Services Group | Operating Segments | Railcars owned one year or less at the time of sale
Revenues:
Total revenues									$ 126.1	$ 404.9	$ 486.3
Operating profit:
Total operating profit									34.1	109.0	136.1
Railcar Leasing and Management Services Group | Operating Segments | Railcars owned more than one year at the time of sale
Operating profit:
Total operating profit									$ 13.5	$ 166.1	$ 92.3