Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Restricted Cash and Cash Equivalents	$ 24,800	$ 30,700
Restricted Cash included in other current assets	3,009	7,900	$ 13,159
Restricted Cash included in other assets	$ 21,784	$ 22,800	$ 12,190