Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 59,278	$ 69,729
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of marketable securities	(1,767)	(521)
Gain on remeasurement of co-investment	0	(21,947)
Company's share of gain on the sales of co-investment	(2,366)	0
Gain on the sales of real estate	(1,503)	(10,870)
(Gain) loss on early retirement of debt	(1,024)	1,450
Co-investments	(280)	3,770
Amortization expense	5,932	5,754
Amortization of discount on notes receivables	(844)	(917)
Amortization of discount on marketable securities	(2,776)	(2,518)
Depreciation	95,175	82,629
Equity-based compensation	2,126	1,925
Changes in operating assets and liabilities:
Prepaid expenses and other assets	802	(4,420)
Accounts payable and accrued liabilities	(2,433)	5,133
Other liabilities	266	195
Net cash provided by operating activities	150,586	129,392
Additions to real estate:
Acquisitions of real estate	(175,950)	(80,502)
Improvements to recent acquisitions	(6,288)	(3,569)
Redevelopment	(17,616)	(17,223)
Revenue generating capital expenditures	(742)	(1,638)
Lessor required capital expenditure	(3,557)	0
Non-revenue generating capital expenditures	(12,349)	(7,040)
Acquisitions of and additions to real estate under development	(9,290)	(17,166)
Acquisition of membership interest in co-investment	0	(85,000)
Dispositions of real estate	9,051	27,800
Changes in restricted cash and deposits	18,290	(1,805)
Purchases of marketable securities	(14,002)	(34,363)
Sales and maturities of marketable securities	20,335	5,070
Purchases of and advances under notes and other receivables	(99,164)	(875)
Collections of notes and other receivables	53,438	7,449
Contributions to co-investments	(101,295)	(114,746)
Distributions from co-investments	57,458	7,430
Net cash used in investing activities	(281,681)	(316,178)
Cash flows from financing activities:
Borrowings under debt agreements	604,472	762,580
Repayment of debt	(495,072)	(671,153)
Additions to deferred charges	(3,838)	(2,622)
Equity related issuance cost	(525)	(274)
Net proceeds from stock options exercised	4,190	1,400
Net proceeds from issuance of common stock	122,905	170,944
Contributions from noncontrolling interest	0	2,400
Distributions to noncontrolling interest	(9,811)	(9,134)
Redemption of noncontrolling interest	(2,017)	(681)
Common and preferred stock dividends paid	(87,598)	(75,431)
Net cash provided by financing activities	132,706	178,029
Net increase in cash and cash equivalents	1,611	(8,757)
Cash and cash equivalents at beginning of year	18,606	12,889
Cash and cash equivalents at end of period	20,217	4,132
Supplemental disclosure of cash flow information:
Cash paid for interest, net of $8.1 million, and $3.9 million capitalized in 2013 and 2012, respectively	50,053	47,575
Supplemental disclosure of noncash investing and financing activities:
Transfer from real estate under development to rental properties	67	4,294
Transfer From Real Estate Under Development To Co Investment Properties	0	148,053
Mortgage notes assumed in connection with purchases of real estate including the loan premiums recorded	0	30,298
Contribution of note receivable to co-investment	0	12,325
Change in accrual of dividends	5,436	4,097
Change in fair value of derivative liabilities	4,820	2,841
Purchase of marketable securities pending settlement	0	8,340
Change in fair value of marketable securities	2,256	845
Change in construction payable	$ 2,339	$ 2,930