Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Property, Plant and Equipment [Line Items]
Restricted Cash and Cash Equivalents	$ 22,500	$ 30,700
Restricted Cash included in other current assets	3,298	7,900	$ 11,600
Restricted Cash included in other assets	$ 19,177	$ 22,800	$ 20,915