Investments Summary of Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Investments [Abstract]
“Available-for-sale” marketable equity securities, cost basis	$ 31,399	$ 21,898
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	107,518	53,625
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	(3,650)	(1,258)
“Available-for-sale” marketable equity securities, at fair value	135,267	74,265
Investments accounted for under cost method	195,303	162,124
Investments	$ 330,570	$ 236,389