Supplemental Cash Flow Information (Reconciliation of Cash, Cash Equivalents and Restricted Cash to Statement of Cash Flows) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents	$ 102,580	$ 53,336
Restricted cash	5,728	1,612
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 108,308	$ 54,948	$ 40,471