Supplemental Cash Flow Information - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 130,521	$ 110,790	$ 91,381
Restricted cash	25,531	29,056	30,548
Cash, cash equivalents and restricted cash	$ 156,052	$ 139,846	$ 121,929	$ 82,203