Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3044-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Segment Reporting - Reconciliation of Total Segment Assets to Total Assets Presented in Consolidated Balance Sheets (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($) segment	Dec. 31, 2019 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	$ 1,912,004	$ 2,229,476
Cash and cash equivalents	$ 120,872	$ 88,824	$ 76,705	$ 54,917
Number of reportable segments \| segment	1	1
Tanker
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets		$ 2,114,451
Ship-to-Ship Transfer
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets		$ 26,201