Annual report pursuant to Section 13 and 15(d)

Note 10 - Fair Value Measurements - Other Assets and Liabilities at Fair Value (Details)

v3.19.1
Note 10 - Fair Value Measurements - Other Assets and Liabilities at Fair Value (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Fair Value, Inputs, Level 1 [Member]    
Equity Method Investments, Fair Value Disclosure  
Fair Value, Inputs, Level 1 [Member] | Anchor Handling Towing Supply [Member]    
Property and equipment, Fair Value Disclosure
Property and equipment, Fair Value Disclosure
Fair Value, Inputs, Level 1 [Member] | Liftboats [Member]    
Property and equipment, Fair Value Disclosure
Property and equipment, Fair Value Disclosure
Fair Value, Inputs, Level 1 [Member] | Offshore Support Vessels, Specialty [Member]    
Property and equipment, Fair Value Disclosure
Property and equipment, Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member]    
Equity Method Investments, Fair Value Disclosure   20,658
Fair Value, Inputs, Level 2 [Member] | Anchor Handling Towing Supply [Member]    
Property and equipment, Fair Value Disclosure 2,000 12,400
Property and equipment, Fair Value Disclosure 2,000 12,400
Fair Value, Inputs, Level 2 [Member] | Liftboats [Member]    
Property and equipment, Fair Value Disclosure 175
Property and equipment, Fair Value Disclosure 175
Fair Value, Inputs, Level 2 [Member] | Offshore Support Vessels, Specialty [Member]    
Property and equipment, Fair Value Disclosure 4,500 750
Property and equipment, Fair Value Disclosure 4,500 750
Fair Value, Inputs, Level 3 [Member]    
Equity Method Investments, Fair Value Disclosure   20,430
Fair Value, Inputs, Level 3 [Member] | Anchor Handling Towing Supply [Member]    
Property and equipment, Fair Value Disclosure
Property and equipment, Fair Value Disclosure
Fair Value, Inputs, Level 3 [Member] | Liftboats [Member]    
Property and equipment, Fair Value Disclosure 134,775
Property and equipment, Fair Value Disclosure 134,775
Fair Value, Inputs, Level 3 [Member] | Offshore Support Vessels, Specialty [Member]    
Property and equipment, Fair Value Disclosure
Property and equipment, Fair Value Disclosure