Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flow from operating activities:
Net income	$ 95,860	$ 70,508
Depreciation and amortization	61,666	62,773
Impairment charges	6,893	3,229
Gain on sale of operating properties	(9,337)	(3,577)
Equity in income of joint ventures, net	(53,261)	(24,111)
Gains on change in control of interests	(3,744)	(23,170)
Equity in income from other real estate investments, net	(3,353)	(11,163)
Distributions from joint ventures and other real estate investments	68,691	43,321
Change in accounts and notes receivable	5,799	7,030
Change in accounts payable and accrued expenses	12,340	18,277
Change in other operating assets and liabilities	(41)	6,768
Net cash flow provided by operating activities	181,513	149,885
Cash flow from investing activities:
Acquisition of operating real estate	(95,321)	(64,717)
Improvements to operating real estate	(21,990)	(18,559)
Improvements to real estate under development	(62)	(110)
Investment in marketable securities	(4,556)	(33,588)
Proceeds from sale/repayments of marketable securities	219	164
Investments and advances to real estate joint ventures	(18,988)	(41,153)
Reimbursements of investments and advances to real estate joint ventures	53,660	20,958
Investment in other real estate investments	(318)	(22,818)
Reimbursements of investments and advances to other real estate investments	3,245	1,050
Investment in mortgage loans receivable		(5,057)
Collection of mortgage loans receivable	6,949	6,022
Investment in other investments		(21,366)
Reimbursements of other investments		463
Proceeds from sale of operating properties	71,336	17,114
Net cash flow used for investing activities	(5,826)	(161,597)
Cash flow from financing activities:
Principal payments on debt, excluding normal amortization of rental property debt	(72,839)	(16,538)
Principal payments on rental property debt	(5,690)	(6,281)
Proceeds from mortgage loan financings		5,374
Proceeds under unsecured revolving credit facility, net	132,288	250,000
Proceeds from issuance of unsecured term loan/notes		78,118
Repayments under unsecured term loan/notes		(178,309)
Financing origination costs	(5,844)	(1,159)
Redemption of/distributions to noncontrolling interests		(2,502)
Dividends paid	(106,762)	(97,744)
Proceeds from issuance of stock	3,303	5,772
Net cash flow (used for) provided by financing activities	(55,544)	36,731
Change in cash and cash equivalents	120,143	25,019
Cash and cash equivalents, beginning of period	148,768	141,875
Cash and cash equivalents, end of period	268,911	166,894
Interest paid during the period (net of capitalized interest of $297 and $219, respectively)	30,979	37,425
Income taxes paid during the period	$ 9,567	$ 111