Investments In Securities (Schedule of Other Investments) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Other Equity Investments
Beginning of period	$ 5,439	$ 4,744
Impairments	0	0
Observable Changes	0	0
Purchases and Additional Commitments Paid	135	1,082
Sales, Returns of Capital and Other Reductions	(107)	(387)
End of period	$ 5,467	$ 5,439