Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) segment
Summary Of Significant Accounting Policies [Line Items]
Operating leases, period for non accrual status	90 days
Operating leases, period of review for impairment	90 days
Number of operating segments | segment	1
Number of reportable segments | segment	1
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Required assets value of financial institutions for cash deposits | $	$ 10,000,000
Operating leases, initial terms	24 months
Direct financing leases, period for non accrual status	90 days
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
U.S. Treaasury instruments maturity period	90 days
Cash deposits, insured amount | $	$ 250
Operating leases, initial terms	120 months
Direct financing leases, period of review for impairment	90 days