Quarterly report pursuant to Section 13 or 15(d)

Assets Held for Sale - Significant Assets Included in Assets Held for Sale (Details)

v3.8.0.1
Assets Held for Sale - Significant Assets Included in Assets Held for Sale (Details) - Disposal Group, Held-for-sale, Not Discontinued Operations
$ in Thousands
Sep. 30, 2017
USD ($)
Long Lived Assets Held-for-sale [Line Items]  
Less: accumulated depreciation $ (113,894)
Total assets held for sale 107,010
South Texas Fabrication Yards  
Long Lived Assets Held-for-sale [Line Items]  
Less: accumulated depreciation (113,596)
Total assets held for sale 104,507
Prospect Shipyard  
Long Lived Assets Held-for-sale [Line Items]  
Less: accumulated depreciation (298)
Total assets held for sale 2,503
Land  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 5,492
Land | South Texas Fabrication Yards  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 5,492
Land | Prospect Shipyard  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 0
Buildings and improvements  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 117,582
Buildings and improvements | South Texas Fabrication Yards  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 117,582
Buildings and improvements | Prospect Shipyard  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 0
Machinery and equipment  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 96,271
Machinery and equipment | South Texas Fabrication Yards  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 93,552
Machinery and equipment | Prospect Shipyard  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 2,719
Furniture and fixtures  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 949
Furniture and fixtures | South Texas Fabrication Yards  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 867
Furniture and fixtures | Prospect Shipyard  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 82
Vehicles  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 610
Vehicles | South Texas Fabrication Yards  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 610
Vehicles | Prospect Shipyard  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 0
Other  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 0
Other | South Texas Fabrication Yards  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 0
Other | Prospect Shipyard  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross $ 0