Investments in and Loans to Joint Ventures (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Ohio Castings [Member]
Results of operations
Revenues	$ 0	$ 5	$ 0	$ 4,454
Gross profit (loss)	(425)	(419)	(912)	(2,399)
Net earnings/(loss)	(202)	(33)	(951)	(2,467)
Axis [Member]
Results of operations
Revenues	11,553	11,089	26,141	25,455
Gross profit (loss)	2,038	2,990	6,154	7,196
Net earnings/(loss)	$ 1,435	$ 2,161	$ 4,905	$ 5,492