CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Statement of Cash Flows [Abstract]
Net cash provided by operating activities:	$ 95,158	$ 80,851
Cash flows from investing activities:
Acquisition of real estate, including intangible assets	(81,535)	(23,000)
Investment in real estate under construction	(34,808)	(52,238)
Capital expenditures	(33,532)	(16,271)
Net proceeds from sale of properties	47,236	72,561
Principal payments received on loans receivable	1,194	1,788
Investment in loans receivable	(16,967)	(5,829)
Investments in non-consolidated entities	0	(1,920)
Distributions from non-consolidated entities in excess of accumulated earnings	15,440	0
Sale of interest in non-consolidated entity	0	7,000
Increase in deferred leasing costs	(4,919)	(3,631)
Change in escrow deposits and restricted cash	(2,337)	4,677
Real estate deposits	(1,259)	(49)
Net cash used in investing activities	(111,487)	(16,912)
Cash flows from financing activities:
Dividends to common and preferred shareholders	(68,233)	(51,450)
Repurchase of exchangeable notes	0	(62,150)
Conversion of convertible notes	(2,663)	0
Principal amortization payments	(23,442)	(19,588)
Principal payments on debt, excluding normal amortization	(338,537)	(139,283)
Change in revolving credit facility borrowings, net	0	35,000
Proceeds from senior notes	247,565	0
Proceeds from term loans	64,000	206,000
Increase in deferred financing costs	(6,539)	(4,638)
Proceeds of mortgages and notes payable	40,000	61,500
Change in restricted cash	(1,573)	(4,498)
Cash distributions to noncontrolling interests	(1,978)	(33,534)
Contributions from noncontrolling interests	0	889
Repurchase of preferred shares	(155,004)	(70,000)
Issuance of common shares, net	302,987	4,291
Net cash provided by (used in) financing activities	56,583	(77,461)
Change in cash and cash equivalents	40,254	(13,522)
Cash and cash equivalents, at beginning of period	34,024	63,711
Cash and cash equivalents, at end of period	$ 74,278	$ 50,189