Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Concentrations (Details)

v3.20.4
Summary of Significant Accounting Policies - Concentrations (Details) - Revenue - Customer concentration - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
USF Program      
Concentration Risk [Line Items]      
Customer concentration (as a percent) 29.00% 24.00%  
Receivables net, current $ 280.5    
Skyhook | Significant customer      
Concentration Risk [Line Items]      
Customer concentration (as a percent) 58.00%   66.00%