Description of Business and Summary of Significant Accounting Policies - Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts
Beginning Balance	$ 2,276	$ 1,318	$ 1,732
Additions Charged to Costs and Expenses	2,159	1,814	1,895
Deductions / Write-Offs	(1,365)	(856)	(2,309)
Ending Balance	$ 3,070	$ 2,276	$ 1,318