Summary of Significant Accounting Policies - Accounts Receivable - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 7,513
Charged to operating expenses	759	$ 787
Write offs of accounts receivable, net of recoveries	(1,110)
Balance at end of period	$ 7,162