Acquisitions - Schedule of Purchase Price Allocation (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
	May 06, 2016	Sep. 30, 2017	May 06, 2017	Dec. 31, 2016
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Goodwill		$ 146,497		$ 145,256
Measurement Period Adjustments
Goodwill		$ 1,241
Ntelos Holding, Corp
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Accounts receivable	$ 48,476		$ 47,234
Inventory	3,810		4,572
Restricted cash	2,167		2,167
Investments	1,501		1,501
Prepaid expenses and other assets	14,835		14,835
Building held for sale	4,950		4,950
Property, plant and equipment	223,900		227,247
Goodwill	151,627		146,383
Other long term assets	10,288		10,843
Total assets acquired	868,954		880,907
Accounts payable	8,648		8,543
Advanced billings and customer deposits	12,477		12,477
Accrued expenses	25,230		23,141
Capital lease liability	418		418
Deferred tax liabilities	124,964		129,291
Retirement benefits	19,461		19,198
Other long-term liabilities	14,056		20,085
Total liabilities assumed	205,254		213,153
Net assets acquired	663,700		667,754
Measurement Period Adjustments
Accounts receivable			(1,242)
Inventory			762
Restricted cash			0
Investments			0
Prepaid expenses and other assets			0
Building held for sale			0
Property, plant and equipment			3,347
Goodwill			(5,244)
Other long term assets			555
Total assets acquired			11,953
Accounts payable			(105)
Advanced billings and customer deposits			0
Accrued expenses			(2,089)
Capital lease liability			0
Deferred tax liabilities			4,327
Retirement benefits			(263)
Other long-term liabilities			6,029
Total liabilities assumed			7,899
Net assets acquired			4,054
Spectrum licenses | Ntelos Holding, Corp
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Finite-lived intangible assets	198,200		198,200
Measurement Period Adjustments
Finite-lived intangible assets			0
Acquired subscribers - wireless | Ntelos Holding, Corp
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Finite-lived intangible assets	198,200		205,946
Measurement Period Adjustments
Finite-lived intangible assets			7,746
Favorable lease intangible assets | Ntelos Holding, Corp
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Finite-lived intangible assets	$ 11,000		17,029
Measurement Period Adjustments
Finite-lived intangible assets			$ 6,029
Affiliate contract expansion | Ntelos Holding, Corp
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	14 years
Sprint and Affiliates | Nonmonetary Exchange of Intangibles | Spectrum licenses
Measurement Period Adjustments
Related party transaction	$ 198,200
Sprint and Affiliates | Nonmonetary Exchange of Intangibles | Acquired subscribers - wireless
Measurement Period Adjustments
Related party transaction	206,000
Sprint and Affiliates | Nonmonetary Exchange of Intangibles | Affiliate contract expansion
Measurement Period Adjustments
Related party transaction	283,300
Sprint and Affiliates | Nonmonetary Exchange of Intangibles | Additional Acquired Subscribers Wireless
Measurement Period Adjustments
Related party transaction	$ 120,900
Sprint and Affiliates | Nonmonetary Exchange of Intangibles | Additional Customer Based Contract Rights
Measurement Period Adjustments
Related party transaction, gain recognition period	5 years