Fair Value Measurements - Fair value hierarchy (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Financial assets:
Current derivative assets	$ 5,084	$ 8,112
Non-current derivative assets	2,401	5,189
Financial liabilities:
Non-current derivative liabilities	1,317
Recurring \| Carrying Value
Financial assets:
Cash and cash equivalents	66,322	66,933
Financial liabilities:
Long-term debt, current and non-current	918,585	909,653
Recurring \| Carrying Value \| Interest rate swap contracts
Financial assets:
Current derivative assets	5,084	8,112
Non-current derivative assets	2,401	5,189
Financial liabilities:
Non-current derivative liabilities	(1,317)
Recurring \| Fair Value
Financial assets:
Cash and cash equivalents	66,322	66,933
Financial liabilities:
Long-term debt, current and non-current	901,003	887,192
Recurring \| Fair Value \| Interest rate swap contracts
Financial assets:
Current derivative assets	5,084	8,112
Non-current derivative assets	2,401	5,189
Financial liabilities:
Non-current derivative liabilities	(1,317)
Recurring \| Fair Value \| Quoted Price in Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	66,322	66,933
Recurring \| Fair Value \| Significant Other Observable Inputs (Level 2)
Financial liabilities:
Long-term debt, current and non-current	901,003	887,192
Recurring \| Fair Value \| Significant Other Observable Inputs (Level 2) \| Interest rate swap contracts
Financial assets:
Current derivative assets	5,084	8,112
Non-current derivative assets	2,401	$ 5,189
Financial liabilities:
Non-current derivative liabilities	$ (1,317)

Fair value portion 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.

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