Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Series A Cumulative Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in-Capital	Retained Earnings (Distributions in excess of net earnings)	Accumulated Other Comprehensive Income	Operating Partnership	Consolidated Joint Venture	Preferred Capital in Consolidated Joint Venture [Member]
Balance (in shares) at Dec. 31, 2017		12,879,475	174,869,046
Balance at Dec. 31, 2017	$ 3,570,278	$ 366,936	$ 1,749	$ 3,208,002	$ (82,566)	$ 8,846	$ 11,181	$ 11,700	$ 44,430
Increase (Decrease) in Owners' Equity
Net income (loss)	23,894				23,689		73	(234)	366
Unrealized loss on interest rate derivatives	17,857					17,857
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0
Contributions from a noncontrolling interest	74							74
Issuance of restricted stock (in shares)			360,416
Issuance of restricted stock	0		$ 4	(4)
Amortization of share-based compensation	2,649			2,649
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock (in shares)			(21,031)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock	(463)		$ (1)	(462)
Forfeiture of restricted stock (in shares)			(2,479)
Forfeiture of restricted stock	0		$ 0	0
Dividends, Preferred Stock	(6,279)				(6,279)
Distributions on common shares and units	(58,244)				(57,988)		(256)
Preferred distributions - consolidated joint venture	(366)								(366)
Balance (in shares) at Mar. 31, 2018		12,879,475	175,205,952
Balance at Mar. 31, 2018	3,549,400	$ 366,936	$ 1,752	3,210,185	(123,144)	26,703	10,998	11,540	44,430
Increase (Decrease) in Owners' Equity
Preferred Stock, Value, Issued	366,936
Balance (in shares) at Dec. 31, 2018		12,879,475	174,019,616
Balance at Dec. 31, 2018	3,496,941	$ 366,936	$ 1,740	3,195,381	(150,476)	16,195	10,827	11,908	44,430
Increase (Decrease) in Owners' Equity
Net income (loss)	28,331				27,253		92	(353)	1,339
Unrealized loss on interest rate derivatives	(14,136)					(14,136)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2,250)					(2,250)
Redemption of Operating Partnership units	(9)						(9)
Contributions from a noncontrolling interest	2,306							2,306
Issuance of restricted stock (in shares)			271,028
Issuance of restricted stock	0		$ 3	(3)
Amortization of share-based compensation	2,828			2,828
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock (in shares)			(19,274)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock	$ (366)		$ 0	(366)
Shares acquired as part of a share repurchase program (in shares)	(602,309)		(602,309)
Shares acquired as part of a share repurchase program	$ (10,561)		$ (6)	(10,555)
Forfeiture of restricted stock (in shares)			(2,034)
Forfeiture of restricted stock	0		$ 0	0
Dividends, Preferred Stock	(6,279)				(6,279)
Distributions on common shares and units	(57,814)				(57,590)		(224)
Preferred distributions - consolidated joint venture	(186)								(186)
Redemption of preferred equity - consolidated joint venture	(45,583)								(45,583)
Balance (in shares) at Mar. 31, 2019		12,879,475	173,667,027
Balance at Mar. 31, 2019	3,393,222	$ 366,936	$ 1,737	$ 3,187,285	$ (187,092)	$ (191)	$ 10,686	$ 13,861	$ 0
Increase (Decrease) in Owners' Equity
Preferred Stock, Value, Issued	$ 366,936