Commitments and Contingencies (Details) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2015 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) location	Sep. 30, 2016 USD ($)	Aug. 31, 2014 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
CAF annual funding	$ 4.4
Period of support service				6 years
Number of eligible locations to offer broadband | location				11,000
Number of locations for interim deployment obligation | location				4,400
Number of locations deployed | location				2,300
Revenue recognized from CAF first year funds		$ 1.1	$ 1.1	$ 3.3	$ 3.3
Jointly owned utility plant
Jointly Owned Utility Plant Interests [Line Items]
Cost of construction						$ 235.0
Company investment in construction costs of plant						$ 25.0
Paid to the cable contractor for the cable build		24.0		$ 24.0
Period of up-front payment received				25 years
Proceeds from sale of capacity		29.5		$ 29.5
Escrow deposit		$ 5.0		$ 5.0
Minimum
Jointly Owned Utility Plant Interests [Line Items]
Downstream broadband service data transfer rate (Mbps)				10
Upstream broadband service data transfer rate (Mbps)				1