Quarterly report pursuant to Section 13 or 15(d)

Organization and Summary of Significant Accounting Policies - Additional Information (Details)

v3.20.1
Organization and Summary of Significant Accounting Policies - Additional Information (Details)
 3 Months Ended 12 Months Ended
Mar. 31, 2020
USD ($)
segment
vessel
ferry
tug
ship
towboat
Dec. 31, 2019
USD ($)
segment
Significant Accounting Policies [Line Items]    
Number of operating segments | segment 2 3
Number of corporate non-operating segments | segment 1 1
Number of harbor tug vessels 3  
Number of regional class research vessels 3  
Number of ferries | ferry 3  
Number of ice-breaker tug vessels | tug 1  
Number of towing, salvage and rescue vessels | ship 5  
Number of OSVs 2  
Number of harbor tug vessels 7  
Number of towboats | towboat 2  
Prepaid contract costs | $ $ 0 $ 0
Other (income) expense, net    
Significant Accounting Policies [Line Items]    
Gain on settlement of contract dispute for project completed in 2015 | $ $ 10,000,000  
Minimum    
Significant Accounting Policies [Line Items]    
Property, plant and equipment, useful life 3 years  
Maximum    
Significant Accounting Policies [Line Items]    
Property, plant and equipment, useful life 25 years