Annual report pursuant to Section 13 and 15(d)

Organization and Summary of Significant Accounting Policies (Details)

v3.8.0.1
Organization and Summary of Significant Accounting Policies (Details)
3 Months Ended 12 Months Ended
Dec. 31, 2017
USD ($)
vessel
$ / shares
Sep. 30, 2017
$ / shares
Jun. 30, 2017
$ / shares
Mar. 31, 2017
$ / shares
Dec. 31, 2016
USD ($)
$ / shares
Sep. 30, 2016
$ / shares
Jun. 30, 2016
$ / shares
Mar. 31, 2016
$ / shares
Dec. 31, 2017
USD ($)
vessel
segment
$ / shares
Dec. 31, 2016
USD ($)
segment
$ / shares
Dec. 31, 2015
USD ($)
segment
$ / shares
Significant Accounting Policies [Line Items]                      
Number of technologically advanced offshore support vessels being constructed | vessel 1               1    
Number of multi-purpose service vessels being constructed | vessel 2               2    
Workers compensation liability $ 4,100,000       $ 3,400,000       $ 4,100,000 $ 3,400,000  
Unapproved change order and claim revenue                 0 0 $ 0
Valuation allowance $ 392,000       $ 0       392,000 0  
Payments made on behalf of employees from withheld, vested shares of common stock                 $ 916,000 $ 217,000 $ 79,000
Number of operating divisions | segment                 3 3 3
Income tax expense                 $ (24,193,000) $ 2,041,000 $ (13,369,000)
Loss per share (in dollars per share) | $ / shares $ (1.63) $ (0.21) $ (0.73) $ (0.44) $ (0.24) $ 0.04 $ 0.37 $ 0.07 $ (3.02) $ 0.24 $ (1.75)
Minimum                      
Significant Accounting Policies [Line Items]                      
Estimated useful life of property, plant and equipment                 3 years    
Maximum                      
Significant Accounting Policies [Line Items]                      
Estimated useful life of property, plant and equipment                 25 years    
Accounting Standards Update 2016-09                      
Significant Accounting Policies [Line Items]                      
Income tax expense                 $ 253,000    
Loss per share (in dollars per share) | $ / shares                 $ 0.02