Investments (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
LB Pipe & Coupling Products, LLC
Schedule of Equity Method Investments [Line Items]
Maximum exposure to loss	$ 5,880	$ 6,008
L B Pipe JV equity method investment | LB Pipe & Coupling Products, LLC
Schedule of Equity Method Investments [Line Items]
Maximum exposure to loss	3,875	3,902
Revolving line of credit | LB Pipe & Coupling Products, LLC
Schedule of Equity Method Investments [Line Items]
Maximum exposure to loss	1,235	1,235
Net investment in direct financing lease
Schedule of Equity Method Investments [Line Items]
Maximum exposure to loss	$ 770	$ 871