v3.7.0.1
Marketable Securities - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Securities Investments [Member]        
Schedule Of Marketable Securities [Line Items]        
Marketable Securities, Realized Gains (Losses) $ (13) $ (10) $ (26) $ (21)
Debt Securities Carried by EGL [Member]        
Schedule Of Marketable Securities [Line Items]        
Marketable Securities, Realized and Unrealized Gains (Losses) (220) (175) (367) (339)
Investment Funds [Member]        
Schedule Of Marketable Securities [Line Items]        
Marketable Securities, Realized and Unrealized Gains (Losses) $ 495 $ 534 $ 1,557 $ 525