Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Related Party Transaction [Line Items]
Balance with Fund Manager		$ 14,842
Percentage of stockholders controlling a related party	10.00%		10.00%
Other Income [Member]
Related Party Transaction [Line Items]
Investment income generated from mutual funds	$ 32
Marketable Securities [Member]
Related Party Transaction [Line Items]
Balance with Fund Manager	$ 15,581	3,792
Cash and Cash Equivalents [Member]
Related Party Transaction [Line Items]
Balance with Fund Manager		$ 11,050