Consolidated Statements Of Equity - USD ($) $ in Thousands	Common Shares [Member] Class A Common Shares [Member]	Common Shares [Member] Class B Common Shares [Member]	Common Shares [Member]	Preferred Shares [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Distributions in Excess of Net Income [Member]	Total Shareholders' Equity [Member]	Noncontrolling Interests Common Units And LTIP Units [Member]	Noncontrolling Interests Consolidated Variable Interest Entity [Member]	Total Noncontrolling Interests [Member]	Total
Balance at Dec. 31, 2015	$ 444			$ 76	$ 1,086,259	$ (466)	$ (408,274)	$ 678,039	$ 31,876	$ (1,760)	$ 30,116	$ 708,155
Balance (in shares) at Dec. 31, 2015			44,457,368	7,600,000					2,319,301
Repurchase of Common Shares	(26)				(49,023)		(2)	(49,051)				(49,051)
Repurchase of Common Shares (in shares)			(2,605,649)
Preferred Shares
Preferred Shares Offering, Net of Costs				$ 77	185,922			185,999				185,999
Preferred Shares Offering, Net of Costs (in shares)				7,700,000
Preferred Share Redemption				$ (46)	(114,954)			(115,000)				(115,000)
Preferred Share Redemption (in shares)				(4,600,000)
Dividends and Distributions declared:
Common Shares							(36,095)	(36,095)				(36,095)
Preferred Shares							(12,006)	(12,006)				(12,006)
Common Units									$ (1,431)		(1,431)	(1,431)
LTIP Units									(1,137)		(1,137)	(1,137)
Dividend Reinvestment Plan					47			47				47
Dividend Reinvestment Plan (in shares)			2,576
Share Based Compensation:
Grants	1				(613)			(612)	$ 1,060		1,060	448
Grants (in shares)			62,943						294,245
Amortization					1,036			1,036	$ 5,082		5,082	6,118
Change in Fair Value of Derivative Instruments						(68)		(68)				(68)
Exercise of Option to Acquire Noncontrolling Interest					(4,515)			(4,515)		2,197	2,197	(2,318)
Net Income (loss)							110,472	110,472	4,710	$ (437)	4,273	114,745
Balance at Sep. 30, 2016	419			$ 107	1,104,159	(534)	(345,905)	758,246	$ 40,160		$ 40,160	798,406
Balance (in shares) at Sep. 30, 2016			41,917,238	10,700,000					2,613,546
Balance at Dec. 31, 2016	418			$ 147	1,198,311	1,373	(364,831)	835,418	$ 44,321			879,739
Balance (in shares) at Dec. 31, 2016			41,770,514	14,700,000					2,838,546
Unit Conversion					392			392	$ (392)
Unit Conversion (in shares)			23,964						(23,964)
Repurchase of Common Shares	(3)				(4,746)			(4,749)				(4,749)
Repurchase of Common Shares (in shares)			(264,805)
Common Stock Issuance
Common Units Issued									$ 4,133			4,133
Common Units Issued, During Peirod, Shares									225,000
Dividends and Distributions declared:
Common Shares							(35,066)	(35,066)				(35,066)
Preferred Shares							(18,124)	(18,124)				(18,124)
Common Units									$ (1,673)			(1,673)
LTIP Units									(1,146)			(1,146)
Dividend Reinvestment Plan					63			63				63
Dividend Reinvestment Plan (in shares)			3,427
Share Based Compensation:
Grants	1				(506)			(505)	$ 779			274
Grants (in shares)			75,876						183,784
Amortization					1,123			1,123	$ 3,445			4,568
Change in Fair Value of Derivative Instruments						(725)		(725)	(47)			(772)
Net Income (loss)							108,157	108,157	5,849			114,006
Balance at Sep. 30, 2017	$ 416			$ 147	$ 1,194,637	$ 648	$ (309,864)	$ 885,984	$ 55,269			$ 941,253
Balance (in shares) at Sep. 30, 2017			41,608,976	14,700,000					3,223,366