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Geographic and segment information: (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) segment	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Segment information
Number of operating segments | segment			1
Revenues	$ 241,949	$ 257,202	$ 735,242	$ 783,813
Long lived assets, net	1,759,075		1,759,075		$ 1,738,349
On-net
Segment information
Revenues	135,267	136,485	397,225	415,865
Off-net
Segment information
Revenues	95,111	111,291	304,558	340,918
Wavelength
Segment information
Revenues	10,179	5,287	26,356	12,230
Non-core
Segment information
Revenues	1,392	4,139	7,103	14,800
North America
Segment information
Revenues	202,228	219,878	619,520	672,983
Long lived assets, net	1,570,519		1,570,519		1,579,495
North America | On-net
Segment information
Revenues	101,746	106,055	300,927	326,108
North America | Off-net
Segment information
Revenues	89,227	104,485	286,086	320,238
North America | Wavelength
Segment information
Revenues	9,934	5,278	25,641	12,230
North America | Non-core
Segment information
Revenues	1,321	4,060	6,866	14,407
Europe
Segment information
Revenues	30,965	29,300	90,510	86,868
Europe | On-net
Segment information
Revenues	25,904	23,801	74,847	70,584
Europe | Off-net
Segment information
Revenues	4,773	5,441	14,822	16,000
Europe | Wavelength
Segment information
Revenues	233		680
Europe | Non-core
Segment information
Revenues	55	58	161	284
South America
Segment information
Revenues	2,311	2,157	6,395	6,109
South America | On-net
Segment information
Revenues	2,158	1,927	5,810	5,396
South America | Off-net
Segment information
Revenues	148	222	563	678
South America | Non-core
Segment information
Revenues	5	8	22	35
Oceania
Segment information
Revenues	6,291	5,714	18,373	17,352
Oceania | On-net
Segment information
Revenues	5,331	4,574	15,273	13,349
Oceania | Off-net
Segment information
Revenues	937	1,118	3,011	3,929
Oceania | Wavelength
Segment information
Revenues	12	9	35
Oceania | Non-core
Segment information
Revenues	11	13	54	74
Africa
Segment information
Revenues	154	153	444	501
Africa | On-net
Segment information
Revenues	128	128	368	428
Africa | Off-net
Segment information
Revenues	26	$ 25	76	$ 73
Europe and other
Segment information
Long lived assets, net	$ 188,556		$ 188,556		$ 158,854

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