Concentration Of Credit Risk (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Concentration Risk [Line Items]
Revenues	$ 81,567	$ 73,890	$ 69,443	$ 69,113	$ 73,521	$ 75,535	$ 74,286	$ 75,511	$ 294,013	$ 298,853	$ 284,924
Single Largest Container Lessee [Member] | Customer Concentration Risk [Member] | Total Revenue [Member]
Concentration Risk [Line Items]
Percentage of operations comprised by segment									17.10%	18.60%	18.20%
Revenues									$ 69,800	$ 65,900	$ 58,000
Single Largest Container Lessee [Member] | Customer Concentration Risk [Member] | Total Billings [Member]
Concentration Risk [Line Items]
Percentage of operations comprised by segment									12.00%	7.00%
Second Largest Container Lessee [Member] | Customer Concentration Risk [Member] | Total Revenue [Member]
Concentration Risk [Line Items]
Percentage of operations comprised by segment									10.20%	11.70%	13.00%
Revenues									$ 41,600	$ 41,400	$ 41,300
Second Largest Container Lessee [Member] | Customer Concentration Risk [Member] | Total Billings [Member]
Concentration Risk [Line Items]
Percentage of operations comprised by segment									11.00%	13.00%