Investments Summary of Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Investments [Abstract]
Available-for-sale equity securities, cost basis	$ 55,433	$ 41,392
Unrealized Gain	50,104	25,076
Unrealized Losses	(4,915)	(5,783)
Available-for-sale equity securities, at fair value	100,622	60,685
Investments accounted for under cost method	384,640	281,792
Investments	$ 485,262	$ 342,477