Supplemental Disclosure to Statements of Cash Flows - Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 96,949	$ 84,923	$ 30,380	$ 11,882
Restricted cash	17,696	10,899	9,366	13,803
Cash, cash equivalents and restricted cash	$ 114,645	$ 95,822	$ 39,746	$ 25,685