Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
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, 2018
USD ($)
Long Lived Assets Held-for-sale [Line Items]  
Less: accumulated depreciation $ (35,271)
Total assets held for sale 42,670
Assets Under Agreement For Sale  
Long Lived Assets Held-for-sale [Line Items]  
Less: accumulated depreciation (24,176)
Total assets held for sale 23,635
Remaining Assets  
Long Lived Assets Held-for-sale [Line Items]  
Less: accumulated depreciation (10,797)
Total assets held for sale 17,146
Shipyard Division Assets  
Long Lived Assets Held-for-sale [Line Items]  
Less: accumulated depreciation (298)
Total assets held for sale 1,889
Land  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 2,157
Land | Assets Under Agreement For Sale  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 2,157
Land | Remaining Assets  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 0
Land | Shipyard Division Assets  
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 31,987
Buildings and improvements | Assets Under Agreement For Sale  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 31,798
Buildings and improvements | Remaining Assets  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 189
Buildings and improvements | Shipyard Division Assets  
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 43,797
Machinery and equipment | Assets Under Agreement For Sale  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 13,856
Machinery and equipment | Remaining Assets  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross 27,754
Machinery and equipment | Shipyard Division Assets  
Long Lived Assets Held-for-sale [Line Items]  
Total assets held for sale, gross $ 2,187