Credit Risk and Allowance for Credit Losses - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of January 1	$ 428	$ 384
Provision for expected credit losses	989	909
(Write-offs) recoveries of accounts receivable	(298)
(Write-offs) recoveries of accounts receivable		70
Balance as of June 30	$ 1,119	$ 1,363