Supplemental Cash Flow Information - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Supplementary Insurance Information [Abstract]
Cash and cash equivalents	$ 86,021	$ 55,306	$ 764,114
Restricted cash	31,947	$ 26,897	60,806
Cash, cash equivalents and restricted cash	$ 117,968		$ 824,920