Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Trading Symbol SMHI  
Entity Registrant Name SEACOR Marine Holdings Inc.  
Entity Central Index Key 0001690334  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period true  
Entity Common Stock, Shares Outstanding   21,765,331
Entity Current Reporting Status Yes  
Entity Shell Company false  
Entity File Number 1-37966  
Entity Tax Identification Number 472564547  
Entity Address, Address Line One 12121 Wickchester  
Entity Address, Address Line Two Suite 500  
Entity Address, City or Town Houston  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 77079  
City Area Code (346)  
Local Phone Number 980-1700