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]	Noncontrolling Interest [Member]	Total Shareholder Equity [Member]
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)	207,113	1,263,278
Stock Issued During Period, Value, Conversion of Units				98	45,599			(45,697)	45,697
Net income	64,035						55,440	8,595	55,440
Other Comprehensive Income	930	8				721		209	721
Redemption of Operating Partnership common units	(9,836)							(9,836)
Dividends declared - common stock	(67,579)						(67,579)		(67,579)
Dividends declared - preferred stock	(21,188)						(21,188)		(21,188)
Issuance of common stock and restricted common stock	329			2	327				329
Cancellation of restricted common stock	(255)				(255)				(255)
Exercise of stock options	4,434			2	4,432				4,434
Accrual under deferred compensation arrangements	29				29				29
Amortization of deferred compensation	1,496				1,496				1,496
Distributions to noncontrolling interests	(17,540)	(4,536)						(17,540)
Adjustment for noncontrolling interests	(1,485)	1,485			(4,242)			2,757	(4,242)
Adjustment to record redeemable noncontrolling interests at redemption value	(7,370)	7,370			(7,370)				(7,370)
Acquire controlling interest in shopping center property	14,505							14,505
Redeemable Noncontrolling Partnership Interests [Roll forward]
Net income		1,620
Proceeds from Contributions from Affiliates	4,042							4,042
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)	164,148	1,270,790
Balance, redeemable noncontrolling partnership interests at Dec. 31, 2012		40,248
Balance at Dec. 31, 2012	1,521,097		25	1,613	1,773,630	6,986	(453,561)	192,404	1,328,693
Net income	45,900						42,037	3,863	42,037
Other Comprehensive Income	1,020	10				869		151	869
Issuance of common stock	209,506			84	209,422				209,506
Dividends declared - common stock	(76,791)						(76,791)		(76,791)
Dividends declared - preferred stock	(22,446)						(22,446)		(22,446)
Issuance of common stock and restricted common stock	0			2	(2)				0
Cancellation of restricted common stock	(705)				(705)				(705)
Amortization of deferred compensation	1,887				1,887				1,887
Distributions to noncontrolling interests	(15,368)	(3,838)						(15,368)
Adjustment for noncontrolling interests	(2,909)	2,909			(29,057)			26,148	(29,057)
Adjustment to record redeemable noncontrolling interests at redemption value	854	(854)			815			39	815
Acquire controlling interest in shopping center property	(41,444)							(41,444)
Redeemable Noncontrolling Partnership Interests [Roll forward]
Net income		1,996
Balance, redeemable noncontrolling partnership interests at Mar. 31, 2013		40,471
Balance at Mar. 31, 2013	$ 1,620,601		$ 25	$ 1,699	$ 1,955,990	$ 7,855	$ (510,761)	$ 165,793	$ 1,454,808