CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 120,129	$ 116,027
Adjustments to net income:
Depreciation and amortization	108,282	86,606
Income from discontinued operations	(6,941)	(7,509)
Gain on sale of real estate		(210)
Amortization of share-based compensation	7,780	6,098
Amortization of net premiums on mortgages payable	(278)	(98)
Provisions for impairment on real estate held for investment		10
Other non-cash adjustments	(301)
Cash provided by discontinued operations:
Real estate	2,139	4,758
Collection of notes receivable by Crest	67	110
Change in assets and liabilities:
Accounts receivable and other assets	5,604	8,672
Accounts payable, accrued expenses and other liabilities	(27,953)	(15,217)
Net cash provided by operating activities	208,528	199,247
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of and improvements to investment properties	(655,128)	(766,148)
Proceeds from the sales of real estate:
Continuing operations	23	593
Discontinued operations	34,283	11,882
Restricted escrow deposits	(4,753)	(2,830)
Net cash used in investing activities	(625,575)	(756,503)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash distributions to common stockholders	(175,719)	(161,276)
Cash dividends to preferred stockholders	(28,962)	(18,190)
Borrowings on lines of credit	908,000	378,100
Payments on lines of credit	(536,400)	(281,500)
Principal payments on mortgages	(11,171)	(138)
Proceeds from preferred stock offerings, net	395,377
Redemption of preferred stock	(127,500)
Proceeds from common stock offerings, net		489,236
Proceeds from bonds issued		150,000
Debt issuance costs	(7,069)	(9,923)
Proceeds from dividend reinvestment and stock purchase plan	2,159	1,242
Other items	(3,039)	(2,359)
Net cash provided by financing activities	415,676	545,192
Net decrease in cash and cash equivalents	(1,371)	(12,064)
Cash and cash equivalents, beginning of period	4,165	17,607
Cash and cash equivalents, end of period	$ 2,794	$ 5,543