Summary of Significant Accounting Policies (Schedule of Differences Between Book Value and Tax Basis of Net Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary of Significant Accounting Policies [Abstract]
Financial statement basis of net assets	$ 4,114	$ 5,704	$ 7,213
Tax basis of net assets (unaudited)	7,492	8,433
Difference	$ (3,378)	$ (2,729)