Accounting Policies And Recent Accounting Pronouncements (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Significant Accounting Policies [Line Items]
Depreciation expense	$ 27,054,000	$ 24,494,000	$ 55,026,000	$ 47,528,000
Net income	$ 12,638,000	$ 3,714,000	$ 17,910,000	$ 10,865,000
Earnings Per Share, Diluted	$ 0.65	$ 0.19	$ 0.93	$ 0.55
Deferred tax asset	$ 1,000,000		$ 1,000,000
40-ft. High Cube Dry Van Container [Member]
Significant Accounting Policies [Line Items]
Residual value	1,400	$ 1,650	1,400	$ 1,650
Reclassification [Member] | 40-ft. High Cube Dry Van Container [Member]
Significant Accounting Policies [Line Items]
Depreciation expense	2,100,000		4,400,000
Net income	$ 2,100,000		$ 4,300,000
Earnings Per Share, Diluted	$ 0.11		$ 0.22