Revenue from Contracts with Customers - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 169,526	$ 158,914	$ 322,714	$ 317,757
Increase in refund liability	1,800		1,800
Remaining performance obligations	3,100		3,100
Revenue remaining performance obligation, per year	800		800
Sprint
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Monthly revenue from contract with customer	1,500		1,500
Revenue from contract with customer, excluding assessed tax	21,000	$ 1,500	21,000	$ 6,000
Contract with customer, refund liability	10,000		$ 10,000		$ 7,000
Deliquent account write-off period			5 months		4 months
COVID-19
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in refund liability	$ 1,200		$ 1,200