Supplemental Cash Flow Information (Reconciliation of Cash, Cash Equivalents and Restricted Cash to Statement of Cash Flows) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents	$ 64,045	$ 35,594	$ 59,925
Restricted cash	1,697	4,877	3,519
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 65,742	$ 40,471	$ 63,444	$ 67,633