Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Details)

v3.19.1
Long-Term Debt (Details) - USD ($)
3 Months Ended 12 Months Ended
Mar. 19, 2019
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Debt Instrument [Line Items]        
Common stock, par value (in dollars per share)   $ 0.01   $ 0.01
Stock repurchase program, remaining authorized repurchase amount   $ 43,500,000    
Debt extinguishment losses, net   (793,000) $ (42,000)  
Payments of debt issuance costs   2,197,000 0  
Repayments of long-term debt   31,396,000 $ 8,071,000  
Letters of credit outstanding, amount   3,000,000    
Interest rate earned on guarantees       0.50%
SEACOR Marine Holdings Inc.        
Debt Instrument [Line Items]        
Guarantor obligations, maximum exposure, undiscounted   $ 36,600,000    
Three Point Two Five Percentage Convertible Notes        
Debt Instrument [Line Items]        
Debt instrument, interest rate, stated percentage   3.25%    
Three Point Zero Percentage Convertible Notes        
Debt Instrument [Line Items]        
Debt instrument, interest rate, stated percentage   3.00%    
Two Point Five Percentage Convertible Notes        
Debt Instrument [Line Items]        
Debt instrument, interest rate, stated percentage   2.50%    
Convertible Debt | Three Point Two Five Percentage Convertible Notes        
Debt Instrument [Line Items]        
Debt instrument, interest rate, stated percentage   3.25%    
Convertible Debt | Three Point Zero Percentage Convertible Notes        
Debt Instrument [Line Items]        
Debt instrument, interest rate, stated percentage   3.00%    
Debt instrument, repurchased face amount   $ 24,000,000    
Repayments of Long-term Debt and Payments for Conversion Option in Convertible Debt   23,200,000    
Debt extinguishment losses, net   (800,000)    
Long-term debt   83,300,000    
Line of Credit | SEACOR Revolving Credit Facility        
Debt Instrument [Line Items]        
Payments of debt issuance costs $ 2,200,000      
Line of credit facility, remaining borrowing capacity   $ 125,000,000    
Line of Credit | SEACOR Revolving Credit Facility | Base Rate | Minimum        
Debt Instrument [Line Items]        
Debt Instrument, Basis Spread on Variable Rate   0.75%    
Line of Credit | SEACOR Revolving Credit Facility | Base Rate | Maximum        
Debt Instrument [Line Items]        
Debt Instrument, Basis Spread on Variable Rate   2.00%    
Line of Credit | SEACOR Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum        
Debt Instrument [Line Items]        
Debt Instrument, Basis Spread on Variable Rate   1.75%    
Line of Credit | SEACOR Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum        
Debt Instrument [Line Items]        
Debt Instrument, Basis Spread on Variable Rate   3.00%    
Line of Credit | SEA-Vista Credit Facility        
Debt Instrument [Line Items]        
Line of credit facility, remaining borrowing capacity   $ 100,000,000    
Line of Credit | Revolving Credit Facility | SEACOR Revolving Credit Facility        
Debt Instrument [Line Items]        
Line of Credit Facility, Maximum Borrowing Capacity $ 125,000,000      
Line of Credit | Revolving Credit Facility | SEA-Vista Credit Facility        
Debt Instrument [Line Items]        
Repayments of long-term debt   6,000,000    
Line of Credit | Secured Debt | Sea-Vista Credit Facility, Term Loan A-1        
Debt Instrument [Line Items]        
Repayments of long-term debt   800,000    
Line of Credit | Secured Debt | Sea-Vista Credit Facility, Term Loan A-2        
Debt Instrument [Line Items]        
Repayments of long-term debt   1,300,000    
Notes Payable, Other Payables        
Debt Instrument [Line Items]        
Repayments of long-term debt   $ 200,000