Investments in Affiliated Companies (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating results for all affiliated companies of GATX
Revenues	$ 646.5	$ 621.2	$ 636.5
Pre tax income reported by affiliates	$ 93.7	$ 71.0	$ 57.2

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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