Investments in Affiliated Companies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Operating results for all affiliated companies of GATX
Revenues	$ 172.0	$ 162.6	$ 343.2	$ 336.1
Pre-tax (loss) income reported by affiliates	$ (9.2)	$ 33.4	$ 1.4	$ 82.5

The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

No definition available.

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