Earnings Per Share (Schedule of Calculation of Numerator and Denominator in Earnings Per Share) (Details) - USD ($)	3 Months Ended																12 Months Ended
	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ (9,914,000)		$ 2,947,000		$ 5,544,000		$ 2,989,000		$ 4,736,000		$ 6,305,000		$ 9,937,000		$ (16,620,000)		$ 1,566,000	$ 4,358,000	$ 19,653,000
Preferred stock dividends																	(10,752,000)	(10,863,000)	(13,652,000)
Preferred stock redemptions costs																		(3,507,000)	(7,890,000)
Net (income) attributable to noncontrolling interests																	(490,000)	(469,000)	(510,000)
Net earnings allocated to unvested shares																	(558,000)	(628,000)	(754,000)
Net (loss) attributable to vested common shares																	$ (10,234,000)	$ (11,109,000)	$ (3,153,000)
Weighted average number of vested common shares outstanding, basic and diluted																	86,341,000	88,420,000	84,168,000
Net (loss) per common share attributable to common shareholders, basic and diluted	$ (0.15)	[1]	$ 0.00	[1]	$ 0.03	[1]	$ 0.00	[1]	$ 0.02	[1]	$ 0.04	[1]	$ 0.08	[1]	$ (0.26)	[1]	$ (0.12)	$ (0.13)	$ (0.04)

[1] Differences between the sum of the four quarterly per share amounts and the annual per share amounts, if any, are attributable to the effect of the weighted average outstanding share calculation for the respective periods.