Description of the business and recent developments: Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Finance leases-fiber lease agreements
Additional finance lease future payments due	$ 24,700
Cash paid for amounts included in the measurement of lease liabilities
Finance lease cost, Amortization of right-of-use assets	26,424	$ 22,850
Interest expense on finance lease liabilities	19,419	18,892
Operating lease cost	18,382	17,362
Total lease costs	64,225	59,104
Operating cash flows from finance leases	(17,366)	(19,121)
Operating cash flows from operating leases	(20,194)	(18,664)
Financing cash flows from finance leases	(23,054)	(23,990)	$ (9,097)
Right-of-use assets obtained in exchange for new finance lease liabilities	50,831	71,622
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 17,853	$ 35,659
Weighted-average remaining lease term - finance leases (in years)	12 years 7 months 6 days	12 years 4 months 24 days
Weighted-average remaining lease term - operating leases (in years)	18 years 8 months 12 days	20 years 2 months 12 days
Weighted average discount rate - finance leases	9.00%	10.30%
Weighted average discount rate - operating leases	5.40%	5.60%
Future minimum payments (principal and interest) under these finance leases
2022	$ 36,211
2023	35,417
2024	35,766
2025	30,519
2026	27,970
Thereafter	252,880
Total minimum lease obligations	418,763
Less-amounts representing interest	(172,893)
Present value of minimum lease obligations	245,870
Current maturities	(17,048)	$ (15,702)
Finance lease obligations, net of current maturities	228,822	203,438
Future minimum payments under these operating lease agreements
2022	17,680
2023	18,359
2024	17,057
2025	14,562
2026	12,585
Thereafter	111,463
Total minimum lease obligations	191,706
Less-amounts representing interest	(67,715)
Present value of minimum lease obligations	123,991
Current maturities	(12,197)	(11,151)
Lease obligations, net of current maturities	$ 111,794	$ 111,318
Minimum
Finance leases-fiber lease agreements
Initial terms	15 years
Maximum
Finance leases-fiber lease agreements
Initial terms	20 years