Summary of Significant Accounting Policies (Schedule of Other, Net) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounting Policies [Abstract]
Interest and dividend income	$ 2,466	$ 1,826	$ 6,533	$ 5,196
Gain on long-term investment	0	0	0	162
Net periodic benefit cost other than the service costs	(254)	(490)	(761)	(1,470)
Impairment of debt securities available for sale	(161)	(53)	(972)	(179)
Impairment of long-term investments	0	0	0	(525)
Other (expense) income	(3)	91	(39)	268
Other, net	$ 2,048	$ 1,374	$ 4,761	$ 3,452