Concentration Of Credit Risk (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Revenues	$ 115,567	$ 115,452	$ 105,705	$ 95,374	$ 94,034	$ 90,161	$ 82,692	$ 81,506	$ 432,098	$ 348,393	$ 294,354
Single Largest Container Lessee [Member] | Customer Concentration Risk [Member] | Total Revenue [Member]
Concentration Risk [Line Items]
Percentage of operations comprised by segment									11.80%	9.70%	6.90%
Revenues									$ 58,000	$ 34,700	$ 20,600
Single Largest Container Lessee [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Percentage of operations comprised by segment									6.00%	6.00%
Second Largest Container Lessee [Member] | Customer Concentration Risk [Member] | Total Revenue [Member]
Concentration Risk [Line Items]
Percentage of operations comprised by segment									8.40%	10.50%	10.60%
Revenues									$ 41,300	$ 37,500	$ 31,700
Second Largest Container Lessee [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Percentage of operations comprised by segment									15.00%	9.00%