Interest and Other Income - Other Income (Expense), Net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Realized gain (loss) on sale of marketable securities, net	$ (1,001)	$ 1,863	$ 4,066	$ 1,834
Realized loss on financial instrument obligation	(83)	0	(752)	0
Realized loss upon change to equity method at fair value	0	0	(568)	0
Foreign exchange loss	(223)	0	(394)	0
Loss on extinguishment of debt	0	(463)	0	(463)
Other	8	67	(69)	37
Other income (expense), net	$ (1,299)	$ 1,467	$ 2,283	$ 1,408