Supplemental Cash Flow Information - Reconciliation of Cash, Cash Equivalents and Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 16,600	$ 14,114	$ 21,808	$ 8,817
Restricted cash and cash equivalents - long-term	3,532	3,409	3,007	2,258
Cash, cash equivalents and restricted cash and cash equivalents	$ 20,132	$ 17,523	$ 24,815	$ 11,075