v3.25.4

Related party transactions: (Details) $ in Thousands			1 Months Ended	12 Months Ended
Related party transactions: (Details) $ in Thousands	Jul. 25, 2023 USD ($) ft²	Apr. 01, 2023	May 31, 2015	Dec. 31, 2025 USD ($) ft²	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Amendment
Related party transactions
Area of land \| ft²	7,369
Notice period for cancellation of lease	60 days
Operating lease income \| $	$ 162,118
Amendment \| Auditorium suitable for training
Related party transactions
Area of land \| ft²	4,987
Amendment \| Data center in building
Related party transactions
Area of land \| ft²	2,382
Related party \| Office Lease
Related party transactions
Payment made for rent and related costs \| $				$ 3,200	$ 3,300	$ 2,800
Related party \| Office Lease \| Sodium LLC
Related party transactions
Fixed annual rent \| $				$ 1,000
Lease term (in years)			5 years
Notice period for cancellation of lease			60 days
Related party \| Office Lease \| Thorium LLC
Related party transactions
Area of land \| ft²				54,803
Lease term (in years)		5 years
Notice period for cancellation of lease		60 days
Operating lease income payments \| $				$ 1,200
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]				Operating Income (Loss)
Related party \| Network Operations Lease \| Germanium LLC
Related party transactions
Area of land \| ft²				1,587
Lease term (in years)		5 years
Notice period for cancellation of lease		60 days
Operating lease income \| $				$ 34,914

Represents the notice period required for cancellation of lease Lessee, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of the fixed annual rent per year under lease agreement.

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Area of land held.

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Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Indicates line item in statement of income or comprehensive income that includes operating lease income.

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Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable.

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Amount of operating lease income from lease payments paid and payable to lessor. Excludes variable lease payments not included in measurement of lease receivable.

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- Definition

Cash payments to lessor's for use of assets under operating leases.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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COGENT COMMUNICATIONS HOLDINGS, INC. 10-K