| Cover | Aug. 09, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 9, 2021 |
| Entity File Number | 1-37836-1 |
| Entity Registrant Name | INTERNATIONAL SEAWAYS, INC. |
| Entity Central Index Key | 0001679049 |
| Entity Tax Identification Number | 98-0467117 |
| Entity Incorporation, State or Country Code | 1T |
| Entity Address, Address Line One | 600 Third Avenue |
| Entity Address, Address Line Two | 39th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10016 |
| City Area Code | 212 |
| Local Phone Number | 578-1600 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | true |
| Common Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock (no par value) |
| Trading Symbol | INSW |
| Security Exchange Name | NYSE |
| Notes 8. 5 Percent Senior Due 2023 [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | 8.5% Senior Notes due 2023 |
| Trading Symbol | INSW - PA |
| Security Exchange Name | NYSE |
