Asset Impairments and Assets Held for Sale Asset Held For Sale (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Long Lived Assets Held-for-sale [Line Items]
Asset Impairment Charges	$ 0.3	$ 6.6	$ 9.0
Assets Held-for-sale, Long Lived, Fair Value Disclosure	4.8	3.4
Portfolio Management [Member]
Long Lived Assets Held-for-sale [Line Items]
Asset Impairment Charges	0.0	6.2	4.5
Rail North America [Member]
Long Lived Assets Held-for-sale [Line Items]
Asset Impairment Charges	0.3	0.4	0.6
Rail International [Member]
Long Lived Assets Held-for-sale [Line Items]
Asset Impairment Charges	0.0	0.0	3.9
Changes Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Long Lived Assets Held-for-sale [Line Items]
Asset Impairment Charges	$ 0.0		3.0
Changes Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member] | Railcars [Member] | Rail International [Member]
Long Lived Assets Held-for-sale [Line Items]
Asset Impairment Charges			0.9
Changes Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member] | Facility Closing [Member] | Rail International [Member]
Long Lived Assets Held-for-sale [Line Items]
Asset Impairment Charges		$ 0.0	$ 3.0