Consolidated Statements Of Equity (USD $) In Thousands, except Share data, unless otherwise specified	Common Shares [Member] Class A Common Shares [Member]	Preferred Shares [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Distributions in Excess of Net Earnings [Member]	Total Shareholders' Equity [Member]	Noncontrolling Interests Common Units [Member]	Noncontrolling Interests Consolidated Joint Ventures [Member]	Noncontrolling Interests Consolidated Variable Interest Entity [Member]	Noncontrolling Interests [Member]	Redeemable Noncontrolling Interests Common Units [Member]	Total
Balance, redeemable noncontrolling interests at Dec. 31, 2011											$ 14,955
Balance at Dec. 31, 2011	1,699	70	1,041,027	(1,151)	(310,974)	730,671	16,864	307		17,171		747,842
Unit Conversion	1		375			376	(376)			(376)
Reclassification / Reallocation of Noncontrolling Interest			(528)			(528)					528	(528)
Common Stock Issuance [Abstract]
Common Stock Offering, net of costs	240		128,430			128,670						128,670
Common Stock Option Cancellation	25,000		(25,000)
Dividends and Distributions declared:
Common Stock ($0.18 per share)					(34,217)	(34,217)						(34,217)
Preferred Stock					(10,500)	(10,500)						(10,500)
Common Units ($0.18 per share)							(748)			(748)	(552)	(748)
Dividend Reinvestment Plan			16			16						16
Stock Based Compensation
Grants	20		2,428			2,448						2,448
Amortization			5,004			5,004						5,004
Consolidation of Variable Interest Entity									956	956		956
Deconsolidation of Consolidated Joint Ventures								(307)		(307)		(307)
Change in Fair Value of Derivative Instruments				(1,096)		(1,096)						(1,096)
Net Income (Loss)					15,592	15,592	115		(423)	(308)	85	15,284
Balance, redeemable noncontrolling interests at Sep. 30, 2012											15,016
Balance at Sep. 30, 2012	1,985	70	1,176,727	(2,247)	(340,099)	836,436	15,855		533	16,388		852,824
Balance, redeemable noncontrolling interests at Dec. 31, 2012											15,321	15,321
Balance at Dec. 31, 2012	1,986	70	1,178,292	(1,786)	(348,734)	829,828	15,484		476	15,960		845,788
Unit Conversion	1		(234)			(233)	(767)			(767)		(1,000)
Reclassification / Reallocation of Noncontrolling Interest							15,321			15,321	(15,321)	15,321
Preferred Stock
Preferred Stock Offering, net of costs		30	72,340			72,370						72,370
Preferred Stock Redemption		(24)	(59,976)			(60,000)						(60,000)
Dividends and Distributions declared:
Common Stock ($0.18 per share)					(37,572)	(37,572)						(37,572)
Preferred Stock					(11,022)	(11,022)						(11,022)
Common Units ($0.18 per share)							(1,254)			(1,254)		(1,254)
Dividend Reinvestment Plan			27			27						27
Stock Based Compensation
Grants	40		285			325						325
Amortization			8,026			8,026						8,026
Change in Fair Value of Derivative Instruments				1,364		1,364						1,364
Net Income (Loss)					13,337	13,337	2		(630)	(628)		12,709
Balance at Sep. 30, 2013	$ 2,027	$ 76	$ 1,198,760	$ (422)	$ (383,991)	$ 816,450	$ 28,786		$ (154)	$ 28,632		$ 845,082