Income (Loss) 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
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
class a units	856,000				877,000				856,000	877,000	885,000
Income (Loss) before Gain (Loss) on Sale of Properties									$ 100,238,000	$ 70,077,000	$ 59,388,000
minority interest partnership units outstanding	856,409								856,409
Restricted Stock Units outstanding									46,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (1,364,000)	$ (2,137,000)	$ (1,677,000)	$ (2,280,000)	$ 27,199,000	$ 8,354,000	$ (5,278,000)	$ 14,263,000	$ (7,458,000)	44,538,000	28,667,000
Gains (Losses) on Sales of Investment Real Estate									1,567,000	69,705,000	37,635,000
Operating Income (Loss)	25,149,000	26,086,000	24,655,000	24,348,000	22,912,000	15,275,000	17,013,000	14,877,000	101,805,000	139,782,000	97,023,000
Net Income (Loss) Attributable to Parent									(7,244,000)	43,467,000	27,681,000
Gain (Loss) on Sales of Loans, Net									954,000	0	0
Gain (Loss) on Extinguishment of Debt									(84,000)	0	(888,000)
Dividends, Preferred Stock									(113,772,000)	(86,741,000)	(63,651,000)
Deemed noncash dividend									(768,000)	(229,000)	(63,000)
NetIncomeAllocatedToUnvestedRestrictedShares									17,000	16,000	15,000
Income (Loss) Attributable to Noncontrolling Interest, before Tax									214,000	(1,071,000)	(986,000)
Interest Expense									111,964,000	95,564,000	67,468,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)									1,831,000	320,000	0
Net Income (Loss) Available to Common Stockholders, Basic	$ (32,536,000)	$ (31,529,000)	$ (28,655,000)	$ (28,313,000)	$ 2,641,000	$ (14,227,000)	$ (26,068,000)	$ (5,636,000)	$ (121,033,000)	$ (43,290,000)	$ (35,985,000)
Weighted Average Number of Shares Outstanding, Diluted	45,934,000	44,703,000	43,703,000	42,680,000	42,046,000	40,300,000	39,383,000	39,098,000	44,265,000	40,032,000	31,926,000
Preferred Stock, Dividend Rate, Percentage									6.00%
Incremental Common Shares from conversion of outstanding units	30,574,000								30,574,000
Share-based Compensation									$ 1,223,000	$ 1,703,000	$ 3,470,000
Earnings Per Share, Basic	$ (0.71)	$ (0.71)	$ (0.66)	$ (0.66)	$ 0.06	$ 0.35	$ 0.66	$ (0.14)	$ (2.73)	$ (1.08)	$ (1.13)
ClassBUnits [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period										256,087
Share-based Compensation										$ 93,000
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	13,000				12,000				13,000	12,000	12,000
Share-based Compensation									$ 13,000
Series A [Member] | Minimum [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred Stock, Dividend Rate, Percentage									5.75%
mShares [Domain] | Maximum [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred Stock, Dividend Rate, Percentage									7.50%
Series A Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred Stock, Shares Outstanding	2,028,000				1,608,000				2,028,000	1,608,000	1,222,000
Series M Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred Stock, Shares Outstanding	103,000				44,000				103,000	44,000	15