Annual report pursuant to Section 13 and 15(d)

Document And Entity Information

v3.10.0.1
Document And Entity Information - USD ($)
12 Months Ended
Dec. 31, 2018
Feb. 22, 2019
Jun. 30, 2018
Document And Entity Information [Abstract]      
Entity Registrant Name SEACOR HOLDINGS INC /NEW/    
Entity Central Index Key 0000859598    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Document Type 10-K    
Document Period End Date Dec. 31, 2018    
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   18,344,861  
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 974,248,089