Consolidation Of Variable Interest Entities (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) item	Jun. 30, 2017 USD ($) item	Jun. 30, 2018 USD ($) item	Jun. 30, 2017 USD ($) item	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Variable Interest Entity [Line Items]
Net book value	$ 2,218,212,000		$ 2,218,212,000		$ 2,004,961,000
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Net book value	62,320,000		62,320,000		61,842,000
Cash	24,348,000	$ 15,461,000	24,348,000	$ 15,461,000	$ 20,685,000	$ 30,449,000
Collateralized Financing Obligations [Member]
Variable Interest Entity [Line Items]
Long-term debt	96,400,000		96,400,000
Term Loan [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Long-term debt	$ 2,400,000		$ 2,400,000
Containers [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of types of container fund arrangements | item			2
Number of container portfolios sold | item	0	0	0	0
Net book value	$ 76,300,000		$ 76,300,000
Cash	24,300,000		24,300,000
Gain (loss) recognized on initial consolidation of VIEs			0
Book value of containers sold	$ 7,300,000	$ 7,200,000	$ 15,200,000	$ 7,200,000