Union Contracts (Details)	Mar. 31, 2017 employees
Mansfield OH Works [Member]
Concentration Risk [Line Items]
Entity Number of Employees	300
Dearborn Works [Member]
Concentration Risk [Line Items]
Entity Number of Employees	1,165
Rockport IN Works Production [Member]
Concentration Risk [Line Items]
Entity Number of Employees	190
Rockport IN Works Maintenance [Member]
Concentration Risk [Line Items]
Entity Number of Employees	135
Walbridge Tube [Member]
Concentration Risk [Line Items]
Entity Number of Employees	90
Middletown Works [Member]
Concentration Risk [Line Items]
Entity Number of Employees	1,725

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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