Summary of Significant Accounting Policies (Schedule of Other Income, Net) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accounting Policies [Abstract]
Interest and dividend income	$ 1,452	$ 1,795	$ 2,776	$ 3,535
Gain on long-term investment	0	24	0	224
Impairment of long-term investments	(921)	0	(1,203)	0
Other income (expense)	50	2	55	(1)
Other income, net	$ 581	$ 1,821	$ 1,628	$ 3,758