CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract]
Pool revenues, received from companies accounted for by the equity method	$ 57,062	$ 72,877	$ 211,050	$ 250,909

venues earned from Pools that are equity method investments.

No definition available.

Name:	insw_EquityMethodInvestmentSummarizedFinancialInformationShippingPoolRevenue
Namespace Prefix:	insw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration