Annual report pursuant to Section 13 and 15(d)

Long-Term Debt (Narrative) (Details)

v3.19.3.a.u2
Long-Term Debt (Narrative) (Details)
12 Months Ended
Nov. 20, 2023
Feb. 28, 2020
USD ($)
Dec. 20, 2019
USD ($)
Mar. 19, 2019
USD ($)
Oct. 31, 2018
USD ($)
May 15, 2018
USD ($)
Dec. 20, 2017
Dec. 19, 2017
USD ($)
Jul. 03, 2017
USD ($)
Apr. 15, 2015
USD ($)
Nov. 13, 2013
USD ($)
Dec. 31, 2019
USD ($)
shares
$ / shares
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
May 15, 2025
Dec. 19, 2022
Nov. 19, 2020
Jun. 05, 2019
USD ($)
Dec. 11, 2012
USD ($)
Sep. 24, 2009
USD ($)
Debt Instrument [Line Items]                                        
Common stock, par value (in dollars per share) | $ / shares                       $ 0.01                
Debt extinguishment losses, net                       $ (2,244,000) $ (11,626,000) $ (819,000)            
Payments on long-term debt                       169,625,000 225,541,000              
Payments for conversion option in convertible debt                       146,000 33,000 1,354,000            
Long-term debt acquired in business acquisition                         0 28,725,000            
Letters of credit outstanding amount                       $ 1,200,000                
Guarantee fee income, interest rate earned on outstanding guarantees                       0.50%                
Securities Repurchase Plan, Authorized Repurchase Amount                                   $ 150,000,000.0    
Securities repurchased plan, remaining authorized repurchase amount                       $ 129,900,000                
SEACOR Marine Holdings Inc.                                        
Debt Instrument [Line Items]                                        
Guarantor obligations, maximum exposure, undiscounted                       22,900,000                
Guarantee fee income                       $ 200,000 300,000 600,000            
3.0% Convertible Senior Notes                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                       3.00%                
2.5% Convertible Senior Notes | Debt Instrument, Conversion Option                                        
Debt Instrument [Line Items]                                        
Payments for conversion option in convertible debt                         1,400,000              
3.25% Convertible Senior Notes                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                       3.25%                
Convertible Debt                                        
Debt Instrument [Line Items]                                        
Common stock, par value (in dollars per share) | $ / shares                       $ 0.01                
Convertible Debt | 3.0% Convertible Senior Notes                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                       3.00%                
Aggregate principal amount                     $ 230,000,000.0                  
Bond trading price triggering contingent interest                     1,200                  
Individual bond, face value                     $ 1,000                  
Debt instrument, contingent interest rate                     0.45%                  
Debt instrument, convertible, conversion ratio             0.0125892                          
Debt instrument, convertible, number of equity instruments (in shares) | shares                       629,976                
Debt instrument, convertible, discounts and issuance costs, amortization period                       7 years                
Debt instrument, interest rate, effective percentage                       7.40%                
Debt conversion, original debt, amount           $ 117,800,000                            
Debt instrument, repurchased amount                       $ 57,200,000 4,900,000              
Repayments of long-term debt and payments for conversion option in convertible debt                       56,200,000 4,700,000              
Debt extinguishment losses, net                       $ 2,100,000 $ 5,400,000              
Convertible Debt | 3.0% Convertible Senior Notes | Subsequent Event                                        
Debt Instrument [Line Items]                                        
Debt instrument, repurchased amount   $ 2,200,000                                    
Repayments of long-term debt and payments for conversion option in convertible debt   $ 2,200,000                                    
Convertible Debt | 3.0% Convertible Senior Notes | Debt Instrument, Put Option, Period One | Scenario, Forecast                                        
Debt Instrument [Line Items]                                        
Debt instrument, put option, percentage                                 100.00%      
Convertible Debt | 3.0% Convertible Senior Notes | Debt Instrument, Put Option, Period Two | Scenario, Forecast                                        
Debt Instrument [Line Items]                                        
Debt instrument, redemption price, percentage 100.00%                                      
Convertible Debt | 3.0% Convertible Senior Notes | Debt Instrument, Redemption, Period One                                        
Debt Instrument [Line Items]                                        
Debt instrument, redemption price, percentage                       100.00%                
Convertible Debt | 2.5% Convertible Senior Notes                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                       2.50%                
Aggregate principal amount                                     $ 350,000,000.0  
Bond trading price triggering contingent interest                       $ 1,200                
Individual bond, face value                                     $ 1,000  
Debt instrument, contingent interest rate                                     0.25%  
Debt instrument, convertible, conversion ratio             0.0190381                          
Debt instrument, convertible, number of equity instruments (in shares) | shares                       1,227,101                
Debt instrument, convertible, discounts and issuance costs, amortization period                       5 years                
Debt instrument, interest rate, effective percentage                       2.50% 6.50%              
Debt instrument, repurchased amount                         $ 61,700,000              
Debt extinguishment losses, net                         100,000              
Payments on long-term debt                         60,500,000              
Convertible Debt | 2.5% Convertible Senior Notes | Debt Instrument, Conversion Option                                        
Debt Instrument [Line Items]                                        
Repayments of long-term debt and payments for conversion option in convertible debt                         61,900,000              
Convertible Debt | 2.5% Convertible Senior Notes | Debt Instrument, Put Option, Period One | Scenario, Forecast                                        
Debt Instrument [Line Items]                                        
Debt instrument, put option, percentage                               100.00%        
Convertible Debt | 2.5% Convertible Senior Notes | Debt Instrument, Redemption, Period One                                        
Debt Instrument [Line Items]                                        
Debt instrument, redemption price, percentage                       100.00%                
Convertible Debt | 2.5% Convertible Senior Notes | Put Option                                        
Debt Instrument [Line Items]                                        
Debt instrument, repurchased amount               $ 31,000,000.0                        
Payments on long-term debt               $ 31,000,000.0                        
Convertible Debt | 3.25% Convertible Senior Notes                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                       3.25%                
Aggregate principal amount           117,800,000                            
Bond trading price triggering contingent interest           1,200                            
Individual bond, face value           $ 1,000                            
Debt instrument, contingent interest rate           0.45%                            
Debt instrument, convertible, conversion ratio           0.0131920                            
Debt instrument, convertible, number of equity instruments (in shares) | shares                       1,553,780                
Debt instrument, convertible, discounts and issuance costs, amortization period                       7 years                
Debt instrument, interest rate, effective percentage                       7.20%                
Payments of debt issuance costs           $ 2,500,000                            
Long-term debt, net of discount           95,100,000                            
Debt issuance costs, gross, carrying amount of liability component           2,000,000.0                            
Debt instrument, convertible, carrying amount of equity component           22,700,000                            
Debt issuance costs, gross, carrying amount of equity component           $ 500,000                            
Convertible Debt | 3.25% Convertible Senior Notes | Debt Instrument, Put Option, Period One | Scenario, Forecast                                        
Debt Instrument [Line Items]                                        
Debt instrument, put option, percentage                             100.00%          
Convertible Debt | 3.25% Convertible Senior Notes | Debt Instrument, Redemption, Period One                                        
Debt Instrument [Line Items]                                        
Debt instrument, redemption price, percentage                       100.00%                
Senior Notes | 7.375% Senior Notes                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                       7.375%                
Aggregate principal amount                                       $ 250,000,000.0
Debt instrument, repurchased amount         $ 147,400,000               5,700,000 7,600,000            
Debt extinguishment losses, net                         (6,100,000) (200,000)            
Payments on long-term debt         153,000,000.0               5,900,000 7,700,000            
Loss on repurchase of debt instrument         $ 5,600,000                              
Line of Credit | SEACOR Revolving Credit Facility                                        
Debt Instrument [Line Items]                                        
Payments of debt issuance costs       $ 2,200,000                                
Line of Credit | SEACOR Revolving Credit Facility | Revolving Credit Facility                                        
Debt Instrument [Line Items]                                        
Payments on long-term debt                       $ 25,000,000.0                
Line of credit facility, maximum borrowing capacity       $ 125,000,000.0                                
Line of credit facility, unused capacity, commitment fee percentage                       0.50%                
Proceeds from issuance of long-term debt                       $ 25,000,000.0                
Line of credit facility, current borrowing capacity                       $ 125,000,000.0                
Line of Credit | SEACOR Revolving Credit Facility | 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 | 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 | SEACOR Revolving Credit Facility | 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 | Revolving Credit Facility | Base Rate | Maximum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate                       2.00%                
Line of Credit | SEA-Vista 2015 Credit Facility                                        
Debt Instrument [Line Items]                                        
Debt extinguishment losses, net                       $ (100,000)                
Payments of debt issuance costs                   $ 3,100,000                    
Line of credit facility, maximum borrowing capacity                   300,000,000.0                    
Line of Credit | SEA-Vista 2015 Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate                       2.00%                
Line of Credit | SEA-Vista 2015 Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate                       2.75%                
Line of Credit | SEA-Vista 2015 Credit Facility | Base Rate | Minimum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate                       1.25%                
Line of Credit | SEA-Vista 2015 Credit Facility | Base Rate | Maximum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate                       1.75%                
Line of Credit | SEA-Vista 2015 Credit Facility | Revolving Credit Facility                                        
Debt Instrument [Line Items]                                        
Payments on long-term debt                       $ 6,000,000.0 39,000,000.0 85,900,000            
Line of credit facility, maximum borrowing capacity                   100,000,000.0                    
Proceeds from issuance of long-term debt                           44,900,000            
Line of Credit | Sea-Vista 2015 Credit Facility, Term Loan A-1 | Secured Debt                                        
Debt Instrument [Line Items]                                        
Aggregate principal amount                   80,000,000.0                    
Payments on long-term debt                       30,600,000 3,300,000 39,400,000            
Line of Credit | Sea-Vista 2015 Credit Facility, Term Loan A-2 | Secured Debt                                        
Debt Instrument [Line Items]                                        
Aggregate principal amount                   $ 120,000,000.0                    
Debt extinguishment losses, net                           700,000            
Payments on long-term debt                       51,400,000 5,500,000 63,100,000            
Line of Credit | SEA-Vista 2019 Credit Facility                                        
Debt Instrument [Line Items]                                        
Payments of debt issuance costs     $ 2,100,000                                  
Line of credit facility, maximum borrowing capacity     $ 200,000,000.0                                  
Line of Credit | SEA-Vista 2019 Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate     2.00%                                  
Line of Credit | SEA-Vista 2019 Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate     2.75%                                  
Line of Credit | SEA-Vista 2019 Credit Facility | Base Rate | Minimum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate     1.00%                                  
Line of Credit | SEA-Vista 2019 Credit Facility | Base Rate | Maximum                                        
Debt Instrument [Line Items]                                        
Debt instrument, basis spread on variable rate     1.75%                                  
Line of Credit | SEA-Vista 2019 Credit Facility | Revolving Credit Facility                                        
Debt Instrument [Line Items]                                        
Line of credit facility, maximum borrowing capacity     $ 100,000,000.0                                  
Line of credit facility, unused capacity, commitment fee percentage     0.50%                                  
Line of credit facility, current borrowing capacity     $ 100,000,000.0                                  
Line of Credit | SEA-Vista 2019 Credit Facility, Term Loan [Member] | Secured Debt                                        
Debt Instrument [Line Items]                                        
Aggregate principal amount     100,000,000.0                                  
Proceeds from issuance of long-term debt     24,000,000.0                                  
Proceeds from Issuance of Debt to Extinguish Existing Debt     $ 76,000,000.0                                  
Debt instrument, periodic payment, principal, Percent     2.50%                                  
Line of Credit | SEA-Vista 2019 Credit Facility, Term Loan [Member] | Secured Debt | Minimum                                        
Debt Instrument [Line Items]                                        
Debt instrument, prepayment increments     $ 1,000,000.0                                  
Line of Credit | ISH Credit Facility                                        
Debt Instrument [Line Items]                                        
Payments of debt issuance costs                 $ 100,000                      
Line of credit facility, maximum borrowing capacity                 25,000,000.0                      
Line of Credit | ISH Credit Facility | Secured Debt                                        
Debt Instrument [Line Items]                                        
Aggregate principal amount                 20,000,000.0                      
Debt extinguishment losses, net                       100,000                
Payments on long-term debt                       12,200,000 7,800,000              
Debt instrument, periodic payment, principal                 700,000                      
Line of Credit | ISH Credit Facility | Revolving Credit Facility                                        
Debt Instrument [Line Items]                                        
Payments on long-term debt                         5,000,000.0              
Line of credit facility, maximum borrowing capacity                 $ 5,000,000.0                      
Line of credit facility, unused capacity, commitment fee percentage                 0.50%                      
Notes Payable, Other Payables                                        
Debt Instrument [Line Items]                                        
Payments on long-term debt                       $ 600,000 $ 2,100,000 $ 3,000,000.0            
Notes Payable, Other Payables | ISH Acquired Debt                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                         7.00%              
Long-term debt acquired in business acquisition                         $ 3,900,000              
Notes Payable, Other Payables | Equipment and Facility Mortgages | Minimum                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                       3.40%                
Notes Payable, Other Payables | Equipment and Facility Mortgages | Maximum                                        
Debt Instrument [Line Items]                                        
Debt instrument, stated percentage                       6.00%