Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 323,930	$ 387,780	$ 384,980
Restricted cash	183,819	195,792	191,281
Total Cash and cash equivalents and Restricted cash shown in the Consolidated Statements of Cash Flows	$ 507,749	$ 583,572	$ 576,261	$ 525,745