Annual report pursuant to Section 13 and 15(d)

Related Party Transactions (Details)

v3.8.0.1
Related Party Transactions (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
SEACOR Marine Holdings Inc. [Member]      
Related Party Transaction [Line Items]      
Related Party Transaction, Revenues from Transactions with Related Party $ 3.5    
Due from Related Parties, Current 1.4    
Era Group [Member]      
Related Party Transaction [Line Items]      
Related Party Transaction, Revenues from Transactions with Related Party 0.4    
Dry-cargo barge pools [Member] | President [Member]      
Related Party Transaction [Line Items]      
Related party transaction, amounts 0.5 $ 0.8 $ 1.3
Management fees 0.1 0.1 $ 0.1
Payables to related parties $ 0.5 $ 0.5