Summary of Significant Accounting Policies (Schedule of Other, Net) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounting Policies [Abstract]
Interest and dividend income	$ 1,826	$ 1,489	$ 5,196	$ 4,265
Gain on long-term investment	0	190	162	190
Impairment of long-term investments	0	0	(525)	(1,203)
Other expense	(5)	(351)	(15)	(296)
Other, net	$ 1,821	$ 1,328	$ 4,818	$ 2,956