Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Base rent	$ 345,022	$ 298,585	$ 285,716
Recoveries from tenants	169,668	139,537	124,853
Other revenues	14,011	14,278	7,023
Total revenues	528,701	452,400	417,592
Expenses:
Property operating costs	154,064	130,051	117,339
Real estate taxes and insurance	20,180	21,335	14,195
Depreciation and amortization	107,781	104,044	96,780
General and administrative	23,043	18,064	17,181
Impairment of Long-Lived Assets to be Disposed of	0	122,472	0
Other expenses	11,781	16,859	9,222
Total expenses	316,849	412,825	254,717
Operating income	211,852	39,575	162,875
Interest:
Expense incurred	(48,294)	(40,510)	(33,583)
Amortization of deferred financing costs	(3,712)	(3,151)	(2,980)
Gain (Loss) on Disposition of Property Plant Equipment	22,833	0	0
Loss on early extinguishment of debt	(1,232)	0	(1,701)
Net (loss) income	181,447	(4,086)	124,611
Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Redeemable	24,248	(5,993)	18,704
Net (loss) income attributable to controlling interests	157,199	1,907	105,907
Preferred stock dividends	(20,739)	(27,245)	(27,245)
Other Preferred Stock Dividends and Adjustments	(12,495)	0	0
Net (loss) income attributable to common shares	123,965	(25,338)	78,662
Net income attributable to common units	$ 148,213	$ (31,331)	$ 97,366
Earnings per share – basic:
Net income attributable to common shares	$ 1.69	$ (0.40)	$ 1.19
Weighted average common shares outstanding	73,003,164	65,184,013	65,486,108
Earnings per share – diluted:
Net income attributable to common shares	$ 1.67	$ (0.40)	$ 1.18
Weighted average common shares outstanding	73,839,036	65,184,013	66,086,379
Earnings per unit – basic:
Net income attributable to common units	$ 1.69	$ (0.40)	$ 1.19
Earnings per unit – diluted:
Net income attributable to common units	$ 1.67	$ (0.40)	$ 1.18
Subsidiaries [Member]
Revenues:
Base rent	$ 345,022	$ 298,585	$ 285,716
Recoveries from tenants	169,668	139,537	124,853
Other revenues	14,011	14,278	7,023
Total revenues	528,701	452,400	417,592
Expenses:
Property operating costs	154,064	130,051	117,339
Real estate taxes and insurance	20,180	21,335	14,195
Depreciation and amortization	107,781	104,044	96,780
General and administrative	23,043	18,064	17,181
Impairment of Long-Lived Assets to be Disposed of	0	122,472	0
Other expenses	11,781	16,859	9,222
Total expenses	316,849	412,825	254,717
Operating income	211,852	39,575	162,875
Interest:
Expense incurred	(48,294)	(40,510)	(33,583)
Amortization of deferred financing costs	(3,712)	(3,151)	(2,980)
Gain (Loss) on Disposition of Property Plant Equipment	22,833	0	0
Loss on early extinguishment of debt	(1,232)	0	(1,701)
Net (loss) income	181,447	(4,086)	124,611
Preferred stock dividends	(20,739)	(27,245)	(27,245)
Other Preferred Stock Dividends and Adjustments	(12,495)	0	0
Net income attributable to common units	$ 148,213	$ (31,331)	$ 97,366
Earnings per unit – basic:
Net income attributable to common units	$ 1.69	$ (0.40)	$ 1.19
Weighted average common units outstanding	87,284,564	80,599,199	81,053,127
Earnings per unit – diluted:
Net income attributable to common units	$ 1.67	$ (0.40)	$ 1.18
Weighted average common units outstanding	88,120,436	80,599,199	81,653,398