XML 60 R48.htm IDEA: XBRL DOCUMENT v3.19.1
Inventories (Inventories) (Details) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Inventory Disclosure [Abstract]    
Raw materials and construction materials $ 29,878 $ 30,006
Work in process 9,565 12,315
Inventories $ 39,443 $ 42,321