Summary of Significant Accounting Policies Tax (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income and other tax expense (benefit)	$ 478	$ 1,613	$ 917
Tax Treatment Of Dividends And Distributions Ordinary Dividends	$ 1.22126	$ 0.722	$ 1.591
Tax Treatment Of Dividends And Distributions Qualified Dividends			0.037
Tax Treatment Of Dividends And Distributions Long Term Capital Gain	0.18959	9.176	0.443
Tax Treatment Of Dividends And Distributions Unrecaptured Section Twelve Hundred And Fifty Gain	0.10040	3.117	0.139
Distributions declared per Common Share outstanding	$ 1.51125	$ 13.015	$ 2.210
Income, Franchise, and Exise Taxes [Member]
Income and other tax expense (benefit)	$ 478	$ 1,613	$ 917
Discontinued operations, net		12	15
Provision for income, franchise and excise taxes	$ 478	$ 1,625	$ 932