Supplemental Disclosure to Statements of Cash Flows Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 24,211	$ 11,882	$ 14,748	$ 43,642
Restricted cash	14,865	13,803	18,115	12,383
Cash and cash equivalents and restricted cash	$ 39,076	$ 25,685	$ 32,863	$ 56,025