Investments (Schedule of Variable Interest Entities) (Details) - LB Pipe & Coupling Products, LLC - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Equity Method Investments
Maximum exposure to loss	$ 5,754	$ 5,845
LB Pipe JV investments
Schedule of Equity Method Investments
Maximum exposure to loss	3,875	3,875
Revolving line of credit
Schedule of Equity Method Investments
Maximum exposure to loss	1,235	1,235
Net Investment In direct financing lease
Schedule of Equity Method Investments
Maximum exposure to loss	$ 644	$ 735