Consolidated Statements of Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Redeemable Noncontrolling Partnership Interests [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Dividends in Excess of Cumulative Earnings [Member]	Total Shareholders' Equity [Member]	Noncontrolling Interest [Member]	Parent [Member]
Balance, redeemable noncontrolling partnership interests at Dec. 31, 2010		$ 34,379
Balance at Dec. 31, 2010			23	1,479	1,657,507	7,855	(366,526)	1,300,338	223,605	1,523,943
Net income							67,695	67,695	12,875	80,570
Other Comprehensive Income	(243)	(2)				(190)		(190)	(51)	(241)
Conversion of operating partnership special common units to shares of common stock				(1)	(728)			(729)	729
Dividends declared - common stock							(62,303)	(62,303)		(62,303)
Dividends declared - preferred stock	(21,188)						(21,188)	(21,188)		(21,188)
Issuance of common stock and restricted common stock				2	190			192		192
Cancellation of restricted common stock					(184)			(184)		(184)
Exercise of stock options				2	1,952			1,954		1,954
Accrual under deferred compensation arrangements					27			27		27
Amortization of deferred compensation					1,376			1,376		1,376
Contributions from noncontrolling interests	40
Distributions to noncontrolling interests		4,511							22,086	22,086
Adjustment for noncontrolling interests					(2,261)			(2,261)	641	(1,620)
Adjustment to record redeemable noncontrolling interests at redemption value		1,186			(1,186)			(1,186)		(1,186)
Acquire controlling interest in shopping center property	(19,626)
Redeemable Noncontrolling Partnership Interests [Roll forward]
Net income		2,634
Adjustment for noncontrolling interests		1,620
Balance, redeemable noncontrolling partnership interests at Jun. 30, 2011		35,306
Balance at Jun. 30, 2011			23	1,484	1,658,149	7,665	(382,322)	1,284,999	214,255	1,499,254
Balance, redeemable noncontrolling partnership interests at Dec. 31, 2011		32,271
Balance at Dec. 31, 2011	1,470,391		23	1,484	1,657,927	3,425	(399,581)	1,263,278	207,113	1,470,391
Net income							(55,440)	55,440	8,595	64,035
Other Comprehensive Income	938	8				721		721	209	930
Conversion of operating partnership special common units to shares of common stock				(98)	(45,599)			45,697	45,697
Partners' Capital Account, Redemptions									(9,836)	(9,836)
Dividends declared - common stock							(67,579)	(67,579)		(67,579)
Dividends declared - preferred stock	(21,188)						(21,188)	(21,188)		(21,188)
Issuance of common stock and restricted common stock				2	327			329		329
Cancellation of restricted common stock					(255)			(255)		(255)
Exercise of stock options				2	4,432			4,434		4,434
Accrual under deferred compensation arrangements					29			29		29
Amortization of deferred compensation					1,496			1,496		1,496
Contributions from noncontrolling interests	4,042								4,042	4,042
Distributions to noncontrolling interests		4,536							17,540	17,540
Adjustment for noncontrolling interests					(4,242)			(4,242)	2,757	(1,485)
Adjustment to record redeemable noncontrolling interests at redemption value		7,370			(7,370)			(7,370)		(7,370)
Acquire controlling interest in shopping center property	(3,969)								14,505	14,505
Redeemable Noncontrolling Partnership Interests [Roll forward]
Net income		1,620
Adjustment for noncontrolling interests		1,485
Balance, redeemable noncontrolling partnership interests at Jun. 30, 2012		38,218
Balance at Jun. 30, 2012	$ 1,434,938		$ 23	$ 1,586	$ 1,697,943	$ 4,146	$ (432,908)	$ 1,270,790	$ 164,148	$ 1,434,938