Segment Reporting - Selected Financial Data for Segments (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) cell_site	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of cell site towers built | cell_site									208
External revenue
Total operating revenue	$ 161,484	$ 158,731	$ 156,501	$ 154,138	$ 151,617	$ 152,382	$ 153,867	$ 154,125	$ 630,854	$ 611,991	$ 535,288
Operating expenses
Selling, general and administrative									113,222	165,937	133,325
Acquisition, integration and migration expenses									0	11,030	42,232
Depreciation and amortization									166,405	177,007	143,685
Operating Expenses									537,608	565,481	512,762
Operating income (loss)	$ 26,994	$ 28,329	$ 21,169	$ 16,754	$ 18,110	$ 9,475	$ 8,252	$ 10,673	93,246	46,510	22,526
Capital Expenditures									136,641	146,489	173,231
Wireless
External revenue
Total operating revenue									457,639	450,129	384,133
Operating expenses
Capital Expenditures									86,146	82,620	123,400
Cable
External revenue
Total operating revenue									124,197	115,917	106,997
Operating expenses
Capital Expenditures									26,640	34,487	32,400
Wireline
External revenue
Total operating revenue									49,018	45,945	44,158
Operating expenses
Capital Expenditures									16,566	22,581	20,200
Other
External revenue
Total operating revenue									0	0	0
Operating expenses
Capital Expenditures									7,289	6,801	(2,769)
Operating Segments
External revenue
Total operating revenue									668,700
Operating Segments | Wireless
External revenue
Total operating revenue									462,655	455,078	388,753
Operating expenses
Selling, general and administrative									47,538	118,257	95,851
Acquisition, integration and migration expenses										10,793	25,927
Depreciation and amortization									127,521	139,610	107,621
Operating Expenses									369,808	420,939	362,512
Operating income (loss)									92,847	34,139	26,241
Operating Segments | Cable
External revenue
Total operating revenue									128,903	119,162	108,734
Operating expenses
Selling, general and administrative									20,274	19,999	19,248
Acquisition, integration and migration expenses										0	0
Depreciation and amortization									24,644	23,968	23,908
Operating Expenses									105,148	103,316	101,737
Operating income (loss)									23,755	15,846	6,997
Operating Segments | Wireline
External revenue
Total operating revenue									77,142	79,253	74,974
Operating expenses
Selling, general and administrative									7,467	6,923	6,474
Acquisition, integration and migration expenses										0	0
Depreciation and amortization									13,673	12,829	11,717
Operating Expenses									59,277	58,288	54,450
Operating income (loss)									17,865	20,965	20,524
Operating Segments | Other
External revenue
Total operating revenue									0	0	0
Operating expenses
Selling, general and administrative									40,654	23,564	14,492
Acquisition, integration and migration expenses										237	16,305
Depreciation and amortization									567	600	439
Operating Expenses									41,221	24,440	31,236
Operating income (loss)									(41,221)	(24,440)	(31,236)
Intersegment Eliminations
External revenue
Total operating revenue									(37,846)	(41,502)	(37,173)
Operating expenses
Selling, general and administrative									(2,711)	(2,806)	(2,740)
Acquisition, integration and migration expenses										0	0
Depreciation and amortization									0	0	0
Operating Expenses									(37,846)	(41,502)	(37,173)
Operating income (loss)									0	0	0
Capital Expenditures									0	0	0
Intersegment Eliminations | Wireless
External revenue
Total operating revenue									5,016	4,949	4,620
Intersegment Eliminations | Cable
External revenue
Total operating revenue									4,706	3,245	1,737
Intersegment Eliminations | Wireline
External revenue
Total operating revenue									28,124	33,308	30,816
Intersegment Eliminations | Other
External revenue
Total operating revenue									0	0	0
Service revenue
External revenue
Total operating revenue									517,256	558,910	478,485
Service revenue | Wireless
External revenue
Total operating revenue									380,818	431,184	359,769
Service revenue | Cable
External revenue
Total operating revenue									114,917	107,338	99,070
Service revenue | Wireline
External revenue
Total operating revenue									21,521	20,388	19,646
Service revenue | Other
External revenue
Total operating revenue									0	0	0
Equipment revenue
External revenue
Total operating revenue									68,398	10,318	11,540
Equipment revenue | Wireless
External revenue
Total operating revenue									67,510	9,467	10,674
Equipment revenue | Cable
External revenue
Total operating revenue									695	724	736
Equipment revenue | Wireline
External revenue
Total operating revenue									193	127	130
Equipment revenue | Other
External revenue
Total operating revenue									0	0	0
Other
External revenue
Total operating revenue									45,200	42,763	45,263
Other | Wireless
External revenue
Total operating revenue									9,311	9,478	13,690
Other | Cable
External revenue
Total operating revenue									8,585	7,855	7,191
Other | Wireline
External revenue
Total operating revenue									27,304	25,430	24,382
Other | Other
External revenue
Total operating revenue									0	0	0
Cost of services
Operating expenses
Cost of services									194,022	188,721	163,969
Cost of services | Operating Segments | Wireless
Operating expenses
Cost of services									131,166	129,626	103,840
Cost of services | Operating Segments | Cable
Operating expenses
Cost of services									59,935	59,335	58,290
Cost of services | Operating Segments | Wireline
Operating expenses
Cost of services									38,056	38,417	36,272
Cost of services | Operating Segments | Other
Operating expenses
Cost of services									0	39	0
Cost of services | Intersegment Eliminations
Operating expenses
Cost of services									(35,135)	(38,696)	(34,433)
Cost of goods sold
Operating expenses
Cost of services									63,959	22,786	29,551
Cost of goods sold | Operating Segments | Wireless
Operating expenses
Cost of services									63,583	22,653	29,273
Cost of goods sold | Operating Segments | Cable
Operating expenses
Cost of services									295	14	291
Cost of goods sold | Operating Segments | Wireline
Operating expenses
Cost of services									81	119	(13)
Cost of goods sold | Operating Segments | Other
Operating expenses
Cost of services									0	0	0
Cost of goods sold | Intersegment Eliminations
Operating expenses
Cost of services									$ 0	$ 0	$ 0