Concentrations	12 Months Ended
Dec. 31, 2016
Risks and Uncertainties [Abstract]
Concentrations	Concentration of Revenues We derived revenue from a wide range of industries and companies. In 2016, we generated approximately 26% of our total revenues from customers in the petroleum industry, 19% from the chemical industry, 18% from the transportation industry, 9% from food/agriculture industries, and 8% from the mining, minerals and aggregates industry. Our foreign identifiable revenues were primarily derived in Germany, Canada, Poland, Mexico, and Austria. Concentration of Credit Risk We did not have revenue concentrations greater than 10% from any particular customer for any of the years ended December 31, 2016, 2015, and 2014. Under our lease agreements with customers, we typically retain legal ownership of the assets unless such assets have been financed by sale-leasebacks. We perform a credit evaluation prior to approval of a lease contract. Subsequently, we monitor the creditworthiness of the customer and the value of the collateral on an ongoing basis. We maintain an allowance for losses to provide for credit losses inherent in our reservable assets portfolio. Concentration of Labor Force As of December 31, 2016, collective bargaining agreements covered approximately 43% of our employees, of which agreements covering 20% of employees will expire within the next year. The hourly employees at our US service centers are represented by the United Steelworkers. Employees at three of Rail North America's Canadian service centers are represented by Unifor, the union formerly known as the Communication, Energy and Paperworkers Union of Canada, and Employee Shop Committee of Riviere-des-Prairies. The Unifor agreements expired in January 2017 and negotiations are scheduled to begin in February 2017. The unlicensed shipboard personnel on twelve of the ASC vessels are represented by the Seafarers International Union ("SIU"). Licensed personnel on ASC’s vessels, other than captains, are represented by the AMO. The SIU and AMO agreements expired January 15, 2017. SIU membership, representing approximately 5% of our employees, ratified a new agreement in January 2017, which will expire in June 2020. ASC reached a tentative agreement with AMO management in February 2017. The new agreement, which would expire in January 2021 and covers approximately 4% of our employees, must now be ratified by the AMO members. Certain employees of GATX Rail Europe are represented by one union in Germany and three unions in Poland.

Concentration of Revenues

We derived revenue from a wide range of industries and companies. In 2016, we generated approximately 26% of our total revenues from customers in the petroleum industry, 19% from the chemical industry, 18% from the transportation industry, 9% from food/agriculture industries, and 8% from the mining, minerals and aggregates industry. Our foreign identifiable revenues were primarily derived in Germany, Canada, Poland, Mexico, and Austria.

Concentration of Credit Risk

We did not have revenue concentrations greater than 10% from any particular customer for any of the years ended December 31, 2016, 2015, and 2014. Under our lease agreements with customers, we typically retain legal ownership of the assets unless such assets have been financed by sale-leasebacks. We perform a credit evaluation prior to approval of a lease contract. Subsequently, we monitor the creditworthiness of the customer and the value of the collateral on an ongoing basis. We maintain an allowance for losses to provide for credit losses inherent in our reservable assets portfolio.

Concentration of Labor Force

As of December 31, 2016, collective bargaining agreements covered approximately 43% of our employees, of which agreements covering 20% of employees will expire within the next year. The hourly employees at our US service centers are represented by the United Steelworkers. Employees at three of Rail North America's Canadian service centers are represented by Unifor, the union formerly known as the Communication, Energy and Paperworkers Union of Canada, and Employee Shop Committee of Riviere-des-Prairies. The Unifor agreements expired in January 2017 and negotiations are scheduled to begin in February 2017. The unlicensed shipboard personnel on twelve of the ASC vessels are represented by the Seafarers International Union ("SIU"). Licensed personnel on ASC’s vessels, other than captains, are represented by the AMO. The SIU and AMO agreements expired January 15, 2017. SIU membership, representing approximately 5% of our employees, ratified a new agreement in January 2017, which will expire in June 2020. ASC reached a tentative agreement with AMO management in February 2017. The new agreement, which would expire in January 2021 and covers approximately 4% of our employees, must now be ratified by the AMO members. Certain employees of GATX Rail Europe are represented by one union in Germany and three unions in Poland.