Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Details)

v3.19.3
Long-Term Debt (Details) - USD ($)
3 Months Ended 9 Months Ended
Oct. 28, 2019
Mar. 19, 2019
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Jun. 05, 2019
Debt Instrument [Line Items]              
Common stock, par value (in dollars per share)     $ 0.01   $ 0.01    
Securities Repurchase Plan, Authorized Repurchase Amount             $ 150,000,000.0
Securities Repurchase Plan, Remaining Authorized Repurchase Amount     $ 131,700,000   $ 131,700,000    
Repayments of long-term debt         66,685,000 $ 43,967,000  
Debt extinguishment losses, net     (777,000) $ (160,000) (2,073,000) (5,609,000)  
Payments For Conversion Option In Convertible Debt         146,000 5,000  
Payments of debt issuance costs         0 $ 2,495,000  
Letters of credit outstanding, amount     1,300,000   $ 1,300,000    
Interest rate earned on guarantees         0.50%    
SEACOR Marine Holdings Inc.              
Debt Instrument [Line Items]              
Guarantor obligations, maximum exposure, undiscounted     $ 27,000,000.0   $ 27,000,000.0    
Guarantee Fee Income         $ 100,000    
Three Point Zero Percentage Convertible Notes              
Debt Instrument [Line Items]              
Debt instrument, interest rate, stated percentage     3.00%   3.00%    
Three Point Two Five Percentage Convertible Notes              
Debt Instrument [Line Items]              
Debt instrument, interest rate, stated percentage     3.25%   3.25%    
Debt Instrument, Conversion Option | Three Point Zero Percentage Convertible Notes              
Debt Instrument [Line Items]              
Payments For Conversion Option In Convertible Debt         $ 100,000    
Convertible Debt | Three Point Zero Percentage Convertible Notes              
Debt Instrument [Line Items]              
Debt instrument, interest rate, stated percentage     3.00%   3.00%    
Debt instrument, repurchased face amount     $ 55,400,000   $ 55,400,000    
Repayments of Long-term Debt and Payments for Conversion Option in Convertible Debt         54,400,000    
Repayments of long-term debt         54,200,000    
Debt extinguishment losses, net         (2,100,000)    
Long-term Debt, Gross     $ 51,900,000   $ 51,900,000    
Convertible Debt | Three Point Zero Percentage Convertible Notes | Subsequent Event [Member]              
Debt Instrument [Line Items]              
Debt instrument, repurchased face amount $ 1,800,000            
Repayments of Long-term Debt and Payments for Conversion Option in Convertible Debt 1,800,000            
Convertible Debt | Two Point Five Percentage Convertible Notes              
Debt Instrument [Line Items]              
Debt instrument, interest rate, stated percentage     2.50%   2.50%    
Convertible Debt | Three Point Two Five Percentage Convertible Notes              
Debt Instrument [Line Items]              
Debt instrument, interest rate, stated percentage     3.25%   3.25%    
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     $ 100,000,000.0   $ 100,000,000.0    
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     $ 100,000,000.0   $ 100,000,000.0    
Line of Credit | Revolving Credit Facility | SEACOR Revolving Credit Facility              
Debt Instrument [Line Items]              
Line of Credit Facility, Maximum Borrowing Capacity   $ 125,000,000.0          
Line of Credit Facility, Commitment Fee Percentage         0.50%    
Proceeds from Issuance of Long-term Debt         $ 25,000,000.0    
Line of Credit | Revolving Credit Facility | SEACOR Revolving Credit Facility | Subsequent Event [Member]              
Debt Instrument [Line Items]              
Repayments of long-term debt $ 25,000,000.0            
Line of Credit | Revolving Credit Facility | SEA-Vista Credit Facility              
Debt Instrument [Line Items]              
Repayments of long-term debt         6,000,000.0    
Line of Credit | Secured Debt | Sea-Vista Credit Facility, Term Loan A-1              
Debt Instrument [Line Items]              
Repayments of long-term debt         2,200,000    
Line of Credit | Secured Debt | Sea-Vista Credit Facility, Term Loan A-2              
Debt Instrument [Line Items]              
Repayments of long-term debt         3,800,000    
Notes Payable, Other Payables              
Debt Instrument [Line Items]              
Repayments of long-term debt         $ 500,000