Revenues - Revenues Disaggregated by Revenue Stream (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	$ 67,788	$ 39,369
Total revenues	246,915	211,473
Fiber Infrastructure
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	63,984	34,442
Total revenues	66,967	34,812
Fiber Infrastructure | Lit Backhaul
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	33,346	24,252
Fiber Infrastructure | Enterprise and Wholesale
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	15,418	3,479
Fiber Infrastructure | E-Rate and Government
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	14,230	6,951
Fiber Infrastructure | Other
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	990	(240)
Consumer CLEC
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	3,804	4,927
Total revenues	3,804	4,927
ASC 2014-09
Disaggregation Of Revenue [Line Items]
Total revenues	$ 179,127	$ 172,104