Supplemental Disclosure to Statements of Cash Flows Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 17,770	$ 11,882	$ 47,666	$ 43,642
Restricted cash	13,371	13,803	16,824	12,383
Cash and cash equivalents and restricted cash	$ 31,141	$ 25,685	$ 64,490	$ 56,025