Investments (Schedule of Variable Interest Entities) (Details) - LB Pipe & Coupling Products, LLC - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments
Maximum exposure to loss	$ 567	$ 5,845
LB Pipe JV investments
Schedule of Equity Method Investments
Maximum exposure to loss	0	3,875
Revolving line of credit
Schedule of Equity Method Investments
Maximum exposure to loss	0	1,235
Net Investment In direct financing lease
Schedule of Equity Method Investments
Maximum exposure to loss	$ 567	$ 735