Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	$ 652	$ 609	$ 594
Additions Charged to Expense/Against Revenue	1,147	991	727
Deductions	(1,066)	(948)	(712)
Balance at End of Period	$ 733	$ 652	$ 609