Principal Business Activity and Significant Accounting Policies - Receivables and Credit Policy (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Receivables and Credit Policy
Accounts receivable, gross	$ 71,808	$ 45,295
Less: Allowance for doubtful accounts	(431)	(216)
Non-current portion of receivables		(72)
Total accounts receivable, net	71,377	45,007
Trade receivables
Receivables and Credit Policy
Accounts receivable, gross	67,551	43,531
Other receivables
Receivables and Credit Policy
Accounts receivable, gross	$ 4,257	$ 1,764