Segment And Geographic Information (Narrative) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($) segment	Dec. 31, 2013 USD ($)
Property, Plant and Equipment [Line Items]
Number of operating industry segments | segment										1
Number of reportable segments | segment									3
Revenues	$ 65,692	$ 66,117	$ 59,366	$ 58,492	$ 58,810	$ 59,203	$ 55,312	$ 54,264	$ 249,667	$ 227,589	$ 212,405
Net book value	1,748,211				$ 1,564,777				1,748,211	$ 1,564,777
Inter-Segment [Member]
Property, Plant and Equipment [Line Items]
Revenues									0
Railcars [Member]
Property, Plant and Equipment [Line Items]
Net book value	$ 234,400								$ 234,400