Commitments and Contingencies - Universal Services Fund Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2015
Loss Contingencies [Line Items]
Accrued federal fees	$ 2,303	$ 1,434
Civil penalty
Loss Contingencies [Line Items]
Accrued federal fees			$ 2,000
Year 2008 through 2012 | USF Obligations
Loss Contingencies [Line Items]
Accrued federal fees			$ 3,900
Disputed portion | Year 2003 To Year 2007 | USF Obligations
Loss Contingencies [Line Items]
Disputed liability related to reversal of interest and penalties	$ 900