Accounts Receivable - Allowance (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 506	$ 353
Provisions (recoveries) for expected credit losses, net of adjustments	(13)	294
Balance, end of period	$ 493	$ 647