Supplemental Cash Flow Information (Reconciliation of Cash, Cash Equivalents and Restricted Cash to Statement of Cash Flows) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents	$ 35,594	$ 64,982
Restricted cash	4,877	2,651
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 40,471	$ 67,633	$ 86,959