Commitments and Contingencies (Details) $ in Millions	1 Months Ended	3 Months Ended
	Aug. 31, 2015 USD ($)	Mar. 31, 2018 USD ($) location	Mar. 31, 2017 USD ($)
Commitments and Contingencies
CAF annual funding | $	$ 4.4
Period of support service		6 years
Number of eligible locations to offer broadband		11,000
Number of locations for interim deployment obligation		4,400
Number of locations deployed		5,452
Revenue recognized from CAF first year funds | $		$ 1.1	$ 1.1
Minimum
Commitments and Contingencies
Downstream broadband service data transfer rate (Mbps)		10
Upstream broadband service data transfer rate (Mbps)		1