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Long-term debt: (Details) $ in Thousands							1 Months Ended								12 Months Ended
	Jun. 04, 2025 USD ($)	Apr. 11, 2025 USD ($)	Jun. 15, 2024	Jun. 11, 2024 USD ($)	May 02, 2024 USD ($)	May 07, 2021 USD ($)	Nov. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	May 31, 2024 USD ($)	Nov. 30, 2023 USD ($)	May 31, 2023 USD ($)	Nov. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	May 31, 2022 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 17, 2025 USD ($)	Jun. 22, 2022 USD ($)
Long-term debt
Proceeds from issuance of secured debt		$ 170,500
Loss on extinguishment & redemption of 2026 notes															$ 5,606
Debt instrument restricted value		72,600
Debt instrument unrestricted value		$ 97,900
Lease payments															$ 33,843	$ 74,632	$ 77,362
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]															us-gaap:SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
Interest rate swap
Long-term debt
Face amount															$ 4,100	22,300
Interest rate (as a percent)															3.50%
Net liability, prepaid expenses																18,300
Net liability, other long term																4,000
Interest rate swap | Cash
Long-term debt
Margin deposits															$ 4,100
Interest rate swap | Unrestricted cash
Long-term debt
Margin deposits															200
Interest rate swap | Accrued and other current liabilities
Long-term debt
Fair value of interest rate swaps															4,300
2027 Mirror Notes
Long-term debt
Face amount				$ 300,000				$ 300,000							$ 300,000
Interest rate (as a percent)								7.00%							7.00%
Maturity date								Jun. 15, 2027
Proceeds from issuance of secured debt															$ 291,900
Minimum percentage of principal amount entitled for redemption				90.00%
Lease payments															$ 114,600
Percentage of face value															98.50%
2027 Mirror Notes | Minimum
Long-term debt
Percentage of principal amount considered as default debt				25.00%
2027 Mirror Notes | Redemption of some or all the notes
Long-term debt
Redemption price percentage of principal amount redeemed			103.50%
2027 Mirror Notes | If certain events have occurred
Long-term debt
Repurchase price, percentage of principal amount repurchased			101.00%
2027 Mirror Notes | If certain events have not occurred
Long-term debt
Repurchase price, percentage of principal amount repurchased				100.00%
2027 Notes
Long-term debt
Face amount													$ 450,000		$ 450,000				$ 450,000
Interest rate (as a percent)													7.00%		7.00%
Maturity date													Jun. 15, 2027
Proceeds from issuance of secured debt															$ 446,000
Loss on extinguishment & redemption of 2026 notes	$ 5,600
Discount on issuance of debt															2,700
Debt costs															$ 1,300
2027 Notes | June 15, 2024 to June 14, 2025
Long-term debt
Redemption price percentage of principal amount redeemed															103.50%
2026 Notes
Long-term debt
Face amount						$ 500,000
Interest rate (as a percent)															3.50%
Redemption value															$ 500,000
Amount of net proceeds from offering	507,300
Aggregate Principal amount	500,000
Amount of accrued interest redeemed	2,200
Discount on issuance of debt						1,800
Debt costs						1,300
Amount of settlement payment	$ 5,000
Net proceeds						$ 496,900
Secured IPv4 notes
Long-term debt
Face amount					$ 380,400
Proceeds from issuance of secured debt															170,479	198,426
Debt costs															4,000	$ 7,600
Senior secured 2032 notes
Long-term debt
Face amount															$ 600,000			$ 600,000
Interest rate (as a percent)															6.50%			6.50%
Proceeds from issuance of secured debt															$ 597,842
Repurchase price in cash, percentage															100.00%
Minimum percentage of principal amount entitled for redemption															90.00%
Debt costs															$ 2,200
Senior secured 2032 notes | Minimum
Long-term debt
Percentage of principal amount considered as default debt															25.00%
Consolidated leverage ratio															1
Senior secured 2032 notes | Maximum
Long-term debt
Consolidated leverage ratio															6
Senior secured 2032 notes | Redemption of some or all the notes
Long-term debt
Repurchase price, percentage of principal amount repurchased															100.00%
Senior secured 2032 notes | Issuers may redeem up to 40% of notes
Long-term debt
Redemption price percentage															106.50%
Repurchase price, percentage of principal amount repurchased															40.00%
Senior secured 2032 notes | Redemption after July 1, 2028
Long-term debt
Repurchase price, percentage of principal amount repurchased															103.25%
Senior secured 2032 notes | Change in control accompanied by certain rating events
Long-term debt
Repurchase price, percentage of principal amount repurchased															101.00%
Existing IPv4 Notes
Long-term debt
Face amount					$ 206,000										$ 206,000
Interest rate (as a percent)					7.924%										7.924%
Maturity date					May 31, 2054
Proceeds from issuance of secured debt					$ 198,400
Additional interest accrued on percentage of principal amount					5.00%
Percentage of noteholders voting rights to amend covenants		50.00%
Existing IPv4 Notes | Base Rate
Long-term debt
Debt instrument basis spread on variable rate															5.00%
Existing IPv4 Notes | US Treasury (UST) Interest Rate
Long-term debt
Debt instrument basis spread on variable rate															3.40%
Existing IPv4 Notes | Issuance Of Additional Class Notes | Minimum
Long-term debt
Consolidated leverage ratio					1
Existing IPv4 Notes | Issuance Of Additional Class Notes | Maximum
Long-term debt
Consolidated leverage ratio					6.1
Existing IPv4 Notes | Substitute New Ipv4 Addresses | Minimum
Long-term debt
Consolidated leverage ratio		1			1
Existing IPv4 Notes | Substitute New Ipv4 Addresses | Maximum
Long-term debt
Consolidated leverage ratio		7.25			6.1
Existing IPv4 Notes | Dispose Of Ipv Addresses Owned By Ipv Issuer Member Dispose Of Ipv Addresses Owned By Ipv Issuer | Minimum
Long-term debt
Consolidated leverage ratio					1
Existing IPv4 Notes | Dispose Of Ipv Addresses Owned By Ipv Issuer Member Dispose Of Ipv Addresses Owned By Ipv Issuer | Maximum
Long-term debt
Consolidated leverage ratio					7.1
IPv4 New Notes
Long-term debt
Face amount		$ 174,400													$ 174,400
Interest rate (as a percent)		6.646%													6.646%
Maturity date		Apr. 30, 2055
Restriction on restricted cash															$ 26,900
Additional interest accrued on percentage of principal amount		5.00%
IPv4 New Notes | Base Rate
Long-term debt
Debt instrument basis spread on variable rate		5.00%
IPv4 New Notes | US Treasury (UST) Interest Rate
Long-term debt
Debt instrument basis spread on variable rate		3.00%
IPv4 New Notes | Issuance Of Additional Class Notes | Minimum
Long-term debt
Consolidated leverage ratio		1
IPv4 New Notes | Issuance Of Additional Class Notes | Maximum
Long-term debt
Consolidated leverage ratio		7.25
IPv4 New Notes | Dispose Of Ipv Addresses Owned By Ipv Issuer Member Dispose Of Ipv Addresses Owned By Ipv Issuer | Minimum
Long-term debt
Consolidated leverage ratio		1
IPv4 New Notes | Dispose Of Ipv Addresses Owned By Ipv Issuer Member Dispose Of Ipv Addresses Owned By Ipv Issuer | Maximum
Long-term debt
Consolidated leverage ratio		7.25
Installment One | Interest rate swap
Long-term debt
Payment made to counter party									$ 19,600
Net proceeds														$ 21,500
Installment Two | Interest rate swap
Long-term debt
Payment made to counter party											$ 24,200
Net proceeds							$ 19,600			$ 24,200		$ 21,500

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