Financial Highlights (Net Asset Value Based Total Return For A Shareholder) (Details)		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017
Investment Company, Financial Highlights [Abstract]
Total Return	[2]	7.38%	[1]	6.14%

[1] The Company redeemed all 503,988 of its outstanding LTIP Units which it had originally issued under its incentive plans, with each LTIP unitholder receiving in exchange an equal number of OP LTIP Units. While this activity did not affect fully diluted net asset value per common share, it did cause a 1.66% decline in net asset value per common share. The Company's total return for the year ended December 31, 2018 before the effect of this activity was 9.19%.

[2] Total return is calculated assuming reinvestment of distributions at shareholders' equity per share during the period.