Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Feb. 28, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill			$ 149,070	$ 146,497
Waived Management Fees Under Affiliate Agreement Amount Expected To Collect Monthly			4,200
Waived management fees, included in affiliate contract expanse accumulated amortization			38,800	37,800	$ 36,100
Cumulative waived management fees			137,200
Amortization expense			20,500	$ 24,600	$ 27,500
Waived Management Fees Under Affiliate Agreement Amount Expected To Collect			118,400
Big sandy acquisition
Business Acquisition [Line Items]
Aggregate purchase price	$ 10,000
Property, plant and equipment acquired	4,600
Goodwill	2,600
Customer relationships | Big sandy acquisition
Business Acquisition [Line Items]
Subscriber relationship acquired	$ 2,800
FCC Spectrum Licenses
Business Acquisition [Line Items]
Indefinite-lived Intangible Assets Acquired		$ 13,800
Finite-lived Intangible Assets Acquired		$ 4,700
Maximum
Business Acquisition [Line Items]
Waived management fees, included in affiliate contract expanse accumulated amortization			$ 255,600