| Document And Entity Information | Aug. 08, 2019 |
| Document Information [Line Items] | |
| Entity Registrant Name | SEACOR HOLDINGS INC /NEW/ |
| Document Type | 8-K |
| Document Period End Date | Aug. 2, 2019 |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-12289 |
| 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 |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | CKH |
| Security Exchange Name | NYSE |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000859598 |
