Consolidated Statements of Comprehensive Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenues
Lease revenue	$ 1,486.2	$ 1,381.1	$ 1,251.4
Non-dedicated engine revenue	86.7	64.6	37.6
MarineOperatingRevenue	0.0	0.0	6.9
Total Revenues	1,740.4	1,585.5	1,410.9
Expenses
Maintenance Expense	427.7	381.6	344.8
Marine operating expense	0.0	0.0	6.5
Depreciation expense	431.8	402.4	376.3
Operating Lease, Expense	28.9	33.9	36.0
Other operating expense	65.3	57.7	46.6
Selling, general and administrative	252.6	236.3	212.7
Total Expenses	1,206.3	1,111.9	1,022.9
Other Income (Expense)
Net gain on asset dispositions	136.9	138.3	130.3
Interest expense, net	(391.5)	(341.0)	(263.4)
Other expense	(0.4)	(9.5)	(9.4)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	279.1	261.4	245.5
Income Taxes	(63.1)	(60.0)	(58.7)
Share of Affiliates’ Earnings (net of tax)	117.3	82.8	72.4
Net Income	333.3	284.2	259.2
Less: Net Income Attributable to Non-Controlling Interest	0.0	0.0	0.0
Net income attributable to GATX	$ 333.3	$ 284.2	$ 259.2
Share Data
Basic earnings per share (in dollars per share)	$ 9.14	$ 7.80	$ 7.13
Average number of common shares (in shares)	35.8	35.8	35.7
Diluted earnings per share (in dollars per share)	$ 9.12	$ 7.78	$ 7.12
Diluted shares (in shares)	35.9	35.9	35.7
Other Operating Income	$ 167.5	$ 139.8	$ 115.0