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Segment information: (Details) $ in Thousands	3 Months Ended		6 Months Ended
Segment information: (Details) $ in Thousands	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Segment information:
Number of operating segments \| segment			1
Revenues	$ 239,806	$ 148,450	$ 393,395	$ 297,622
Long-lived assets, net	1,663,508		1,663,508		$ 544,439
On-net
Segment information:
Revenues	127,665	111,975	243,808	224,609
Off-net
Segment information:
Revenues	101,984	36,282	139,266	72,668
Wavelength
Segment information:
Revenues	1,585		1,585
Non-core
Segment information:
Revenues	8,572	193	8,736	345
North America
Segment information:
Revenues	205,177	118,698	326,888	236,988
Long-lived assets, net	1,505,413		1,505,413		397,434
North America \| On-net
Segment information:
Revenues	99,822	86,686	188,519	173,128
North America \| Off-net
Segment information:
Revenues	95,239	31,839	128,115	63,548
North America \| Wavelength
Segment information:
Revenues	1,585
North America \| Non-core
Segment information:
Revenues	8,531	173	8,669	312
Europe
Segment information:
Revenues	27,212	24,524	53,095	50,303
Europe \| On-net
Segment information:
Revenues	22,120	20,458	43,967	41,954
Europe \| Off-net
Segment information:
Revenues	5,070	4,046	9,090	8,320
Europe \| Non-core
Segment information:
Revenues	22	20	38	29
South America
Segment information:
Revenues	1,855	1,387	3,534	2,838
South America \| On-net
Segment information:
Revenues	1,652	1,330	3,297	2,722
South America \| Off-net
Segment information:
Revenues	203	57	236	115
South America \| Non-core
Segment information:
Revenues			1	1
Oceania
Segment information:
Revenues	5,360	3,641	9,451	7,122
Oceania \| On-net
Segment information:
Revenues	3,894	3,321	7,649	6,462
Oceania \| Off-net
Segment information:
Revenues	1,447	320	1,774	657
Oceania \| Non-core
Segment information:
Revenues	19		28	3
Africa
Segment information:
Revenues	202	200	427	371
Africa \| On-net
Segment information:
Revenues	177	180	376	343
Africa \| Off-net
Segment information:
Revenues	25	$ 20	51	$ 28
Europe and other
Segment information:
Long-lived assets, net	$ 158,095		$ 158,095		$ 147,005