Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flow from operating activities:
Net income	$ 355,105	$ 305,452
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	275,787	264,436
Impairment charges	34,280	68,126
Deferred taxes	(238)	56,143
Early extinguishment of debt charges	1,753	45,674
Equity award expense	17,836	15,292
Gain on sale of operating properties	(62,102)	(81,873)
Gain on change in control of interests	(71,160)	(53,096)
Equity in income of joint ventures, net	(37,044)	(190,155)
Equity in income from other real estate investments, net	(61,952)	(22,532)
Distributions from joint ventures and other real estate investments	41,071	70,043
Change in accounts and notes receivable	(189)	3,779
Change in accounts payable and accrued expenses	37,884	23,931
Change in Canadian withholding tax receivable	4,138	(5,257)
Change in other operating assets and liabilities	(41,353)	(55,437)
Net cash flow provided by operating activities	493,816	444,526
Cash flow from investing activities:
Acquisition of operating real estate and other related net assets	(110,802)	(181,548)
Improvements to operating real estate	(136,534)	(102,084)
Acquisition of real estate under development	(10,010)	(51,588)
Improvements to real estate under development	(121,764)	(42,042)
Investment in marketable securities	(9,822)	(2,466)
Proceeds from sale of marketable securities	2,442	1,907
Investments in and advances to real estate joint ventures	(26,788)	(50,058)
Reimbursements of investments in and advances to real estate joint ventures	17,529	70,669
Distributions from liquidation of real estate joint ventures		135,648
Return of investment from liquidation of real estate joint ventures		190,102
Investment in other real estate investments	(666)	(233)
Reimbursements of investments and advances to other real estate investments	40,514	11,489
Collection of mortgage loans receivable	760	688
Reimbursements of other investments		500
Proceeds from sale of operating properties	76,869	262,708
Proceeds from sale of development properties		4,551
Net cash flow (used for)/provided by investing activities	(278,272)	248,243
Cash flow from financing activities:
Principal payments on debt, excluding normal amortization of rental property debt	(678,939)	(602,079)
Principal payments on rental property debt	(11,508)	(15,316)
Proceeds from mortgage loan financings	206,000
(Repayments)/proceeds from unsecured revolving credit facility, net	(42)	226,447
Proceeds from issuance of unsecured notes	1,250,000	650,000
Repayments under unsecured term loan/notes	(460,988)	(861,850)
Financing origination costs	(22,975)	(14,033)
Payment of early extinguishment of debt charges	(2,461)	(45,674)
Change in tenants' security deposits	891	1,240
Contributions from noncontrolling interests	1,422
Conversion/distribution of noncontrolling interests	(95,410)	(3,190)
Dividends paid	(381,182)	(354,112)
Proceeds from issuance of stock, net	218,750	306,809
Redemption of preferred stock	(225,000)
Net cash flow used for financing activities	(201,442)	(711,758)
Change in cash and cash equivalents	14,102	(18,989)
Cash and cash equivalents, beginning of period	142,486	189,534
Cash and cash equivalents, end of period	156,588	170,545
Interest paid during the period (net of capitalized interest of $10,671 and $3,762, respectively)	118,736	194,234
Income taxes paid during the period (net of refunds received of $8,323 and $86,100, respectively)	$ (6,694)	$ 34,296