Fair Value of Financial Instruments and Derivatives Instruments - Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative assets / Current assets	$ 0	$ 99
Derivative assets / Non-current assets	2,771	54
Derivative liabilities / Current liabilities	362	582
Derivative liabilities / Non-current liabilities	295	1,396
Not designated as hedging instrument
Derivative [Line Items]
Total derivative assets	2,771	153
Total derivative liabilities	657	1,978
Not designated as hedging instrument \| Foreign Exchange Agreements
Derivative [Line Items]
Derivative assets / Current assets	0	99
Not designated as hedging instrument \| Interest Rate Contracts
Derivative [Line Items]
Derivative assets / Non-current assets	2,771	54
Derivative liabilities / Non-current liabilities	235	1,280
Not designated as hedging instrument \| Bunker Fuel Contracts
Derivative [Line Items]
Derivative liabilities / Current liabilities	290	408
Derivative liabilities / Non-current liabilities	60	116
Not designated as hedging instrument \| Forward Freight Agreements
Derivative [Line Items]
Derivative liabilities / Current liabilities	$ 72	$ 174

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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