Accounting Policies And Recent Accounting Pronouncements (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Significant Accounting Policies [Line Items]
Depreciation expense	$ 27,788,000	$ 29,873,000	$ 82,814,000	$ 77,401,000
Net income	$ 17,587,000	$ (5,451,000)	$ 35,497,000	$ 5,414,000
Earnings Per Share, Diluted	$ 0.90	$ (0.28)	$ 1.83	$ 0.28
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			4,400,000
Net income			$ 4,300,000
Earnings Per Share, Diluted			$ 0.22