Investments Summary of Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Investments [Abstract]
Available-for-sale equity securities, cost basis	$ 36,469	$ 20,022
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	78,400	118,392
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	(2,322)	(793)
Available-for-sale equity securities, at fair value	112,547	137,621
Investments accounted for under cost method	247,503	215,844
Investments	$ 360,050	$ 353,465