Accounts Receivable - Balance and Activity in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Beginning balance	$ 1,295	$ 1,274	$ 880
Additions charged to costs and expenses	6	758	397
Deductions	(184)	(737)	(3)
Ending balance	$ 1,117	$ 1,295	$ 1,274