Annual report pursuant to Section 13 and 15(d)


Cover - USD ($)
12 Months Ended
Dec. 31, 2020
Feb. 23, 2021
Jun. 30, 2020
Cover [Abstract]      
Document Type 10-K/A    
Document Annual Report true    
Document Period End Date Dec. 31, 2020    
Document Transition Report false    
Entity File Number 1-12289    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 13-3542736    
Entity Address, Address Line One 2200 Eller Drive, P.O. Box 13038    
Entity Address, City or Town Fort Lauderdale    
Entity Address, State or Province FL    
Entity Address, Postal Zip Code 33316    
City Area Code 954    
Local Phone Number 523-2200    
Entity Listing, Par Value Per Share Common Stock, par value $.01 per share    
Trading Symbol CKH    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Public Float     $ 538,578,460
Entity Common Stock, Shares Outstanding   20,498,564  
Entity Registrant Name SEACOR HOLDINGS INC /NEW/    
Entity Central Index Key 0000859598    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Amendment Flag false