Summary of Significant Accounting Policies (Schedule of Other, Net) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accounting Policies [Abstract]
Interest and dividend income	$ 1,625	$ 1,452	$ 3,370	$ 2,776
Gain on long-term investment	197	0	162	0
Impairment of long-term investments	(525)	(921)	(525)	(1,203)
Other income (expense)	41	50	(10)	55
Other, net	$ 1,338	$ 581	$ 2,997	$ 1,628