Subsequent Events: (Details) $ in Thousands	May 01, 2023 USD ($)
IP Transit Services Agreement | T-Mobile USA, Inc.,
Subsequent Events
Period of prior written notice	30 days
Subsequent Events | Purchase Agreement | Buyer | Purchased Interests of Wireline Network Holdings LLC
Subsequent Events
Amount payable	$ 1
Acquired cash and cash equivalents	43,400
Working Capital Adjustment	61,100
Estimated payment related to acquired lease obligations	$ 30,800
Percent of amount to be paid in each months 55 to 58 after the Closing Date	25.00%
Subsequent Events | IP Transit Services Agreement | T-Mobile USA, Inc.,
Subsequent Events
Amount payable	$ 700,000
Subsequent Events | IP Transit Services Agreement | T-Mobile USA, Inc., | Equal monthly installments during the first year after the Closing Date
Subsequent Events
Amount payable	350,000
Subsequent Events | IP Transit Services Agreement | T-Mobile USA, Inc., | Equal monthly installments over the subsequent 42 months
Subsequent Events
Amount payable	$ 350,000
Subsequent Events | Transition Services Agreement
Subsequent Events
Agreement term (in years)	2 years
Extension period	1 year
Period of prior written notice	30 days