Consolidated Balance Sheets Parenthetical - USD ($) shares in Millions, $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounts Receivable, Allowance for Credit Loss	$ 15.9	$ 16.0
Restricted cash, including partially-owned subsidiaries of $30.6 and $74.4	129.4	214.7
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	9,539.6	9,272.6
Less accumulated depreciation, including partially-owned subsidiaries of $644.7 and $599.0	$ 2,534.8	$ 2,385.8
Preferred Stock, Shares Authorized	1.5	1.5
Preferred Stock, Shares Subscribed but Unissued	1.5	1.5
Common Stock, Shares Authorized	400.0	400.0
Common Stock [Member]
Common Stock, Shares, Issued	(81.8)	(81.1)
Treasury Stock, Common
Common Stock, Shares, Issued	0.0	(0.0)
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Restricted cash, including partially-owned subsidiaries of $30.6 and $74.4	$ 129.4	$ 214.7
Partially-Owned Subsidiaries [Member]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	1,922.5	1,917.6
Less accumulated depreciation, including partially-owned subsidiaries of $644.7 and $599.0	644.7	599.0
Partially-Owned Subsidiaries [Member] | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Restricted cash, including partially-owned subsidiaries of $30.6 and $74.4	$ 30.6	$ 74.4