Debt (Details 1) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Maturities of GATX's debt obligations
2016	$ 363.7
2017	500.0
2018	533.1
2019	527.4
2020	461.4
Thereafter	3,544.4
Total debt principal	5,930.0	$ 5,358.5
Balance	$ 18.1	$ 23.6
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.84%	0.85%

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of borrowings classified as other, maturing within one year or the normal operating cycle, if longer.

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Weighted average interest rate of short-term debt outstanding calculated at point in time.

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