CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 82,671	$ 75,247
Adjustments to net income:
Depreciation and amortization	70,560	55,104
Income from discontinued operations	(4,858)	(2,661)
Gain on sale of real estate		(155)
Amortization of share-based compensation	5,550	4,347
Amortization of net premiums on mortgages payable	(168)
Other non-cash adjustments	(301)
Cash provided by discontinued operations:
Real estate	1,274	2,454
Collection of notes receivable by Crest	44	72
Change in assets and liabilities:
Accounts receivable and other assets	1,820	7,826
Accounts payable, accrued expenses and other liabilities	(659)	(5,266)
Net cash provided by operating activities	155,933	136,968
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of and improvements to investment properties	(221,959)	(303,764)
Proceeds from the sales of real estate:
Continuing operations		675
Discontinued operations	18,549	4,372
Loans receivable	(3,795)
Restricted escrow deposits	(6,449)	(5,999)
Net cash used in investing activities	(213,654)	(304,716)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash distributions to common stockholders	(116,552)	(106,131)
Cash dividends to preferred stockholders	(18,480)	(12,127)
Borrowings from lines of credit	377,400	38,600
Payments on lines of credit	(431,200)	(38,600)
Principal payments on mortgages	(10,952)
Proceeds from preferred stock offerings, net	395,377
Redemption of preferred stock	(127,500)
Proceeds from common stock offering, net		285,605
Proceeds from bonds issued		150,000
Debt issuance costs	(7,058)	(9,915)
Proceeds from dividend reinvestment and stock purchase plan	1,548	716
Other items	(2,963)	(2,336)
Net cash provided by financing activities	59,620	305,812
Net increase in cash and cash equivalents	1,899	138,064
Cash and cash equivalents, beginning of period	4,165	17,607
Cash and cash equivalents, end of period	$ 6,064	$ 155,671