Other Income (Expense), net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Investment income	$ 921	$ 1,310	$ 2,485	$ 2,899
Realized gain on sales of marketable securities, net	1,828	2,076	1,963	5,067
Realized loss on financial instrument obligations	(97)	(669)	(283)	(669)
Realized loss upon change to equity method at fair value	0	(568)	(2,807)	(568)
Foreign exchange gain (loss)	91	(171)	(197)	(171)
Other	258	(14)	111	(77)
Other income (expense), net	$ 3,001	$ 1,964	$ 1,272	$ 6,481