Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 segment	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments	1
Number of reportable segments	1
Period subject to income tax examination	3 years
Provision for franchise fees and state taxes	$ 3,000	$ 26,000
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Required assets value of financial institutions for cash deposits	10,000,000,000
Operating leases, initial terms	24 months
Operating leases, period for non accrual status	90 days
Direct financing leases, period for non accrual status	90 days
Period of scheduled vessel drydocking	24 months
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
U.S. Treaasury instruments maturity period	90 days
Cash deposits, insured amount	$ 250,000
Operating leases, initial terms	120 months
Operating leases, period of review for impairment	90 days
Direct financing leases, period of review for impairment	90 days
Period of scheduled vessel drydocking	30 months