Consolidated Balance Sheets Parenthetical - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Accounts Receivable, Allowance for Credit Loss	$ 15.6	$ 14.1
Restricted cash, including partially-owned subsidiaries of $58.6 and $31.1	135.1	96.4
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,927.7 and $1,931.6	9,105.6	9,087.2
Less accumulated depreciation, including partially-owned subsidiaries of $568.4 and $525.7	$ 2,258.7	$ 2,118.4
Preferred Stock, Shares Subscribed but Unissued	1,500,000	1,500,000
Preferred Stock, Shares Authorized	1,500,000	1,500,000
Common Stock, Shares Authorized	400,000,000.0	400,000,000.0
Common Stock [Member]
Common Stock, Shares, Issued	(83,300,000)	(111,200,000)
Treasury Stock [Member]
Common Stock, Shares, Issued	0	(100,000)
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Restricted cash, including partially-owned subsidiaries of $58.6 and $31.1	$ 135.1	$ 96.3
Partially-Owned Subsidiaries [Member]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,927.7 and $1,931.6	1,927.7	1,931.6
Less accumulated depreciation, including partially-owned subsidiaries of $568.4 and $525.7	568.4	525.7
Partially-Owned Subsidiaries [Member] | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Restricted cash, including partially-owned subsidiaries of $58.6 and $31.1	$ 58.6	$ 31.1