CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Statement of Cash Flows [Abstract]
Net cash provided by operating activities:	$ 57,132	$ 43,798
Cash flows from investing activities:
Acquisition of real estate, including intangible assets	(81,535)	0
Investment in real estate under construction	(18,047)	(21,976)
Capital expenditures	(17,372)	(7,196)
Net proceeds from sale of properties	1,861	2,357
Principal payments received on loans receivable	716	1,444
Investment in loans receivable	(10,596)	0
Distributions from non-consolidated entities in excess of accumulated earnings	14,975	0
Increase in deferred leasing costs	(2,794)	(2,644)
Change in escrow deposits and restricted cash	308	5,006
Real estate deposits	(192)	(225)
Net cash used in investing activities	(112,676)	(23,234)
Cash flows from financing activities:
Dividends to common and preferred shareholders	(31,285)	(25,244)
Repurchase of exchangeable notes	0	(62,150)
Conversion of convertible notes	(2,663)	0
Principal amortization payments	(18,733)	(15,049)
Principal payments on debt, excluding normal amortization	(147,291)	(115,712)
Change in revolving credit facility borrowings, net	0	20,000
Proceeds from term loan	0	161,000
Increase in deferred financing costs	(4,025)	(4,091)
Proceeds of mortgages and notes payable	40,000	6,500
Cash distributions to noncontrolling interests	(902)	(1,218)
Contributions from noncontrolling interests	0	889
Repurchase of preferred shares	0	(1,461)
Issuance of common shares, net	297,823	2,145
Net cash provided by (used in) financing activities	132,924	(34,391)
Change in cash and cash equivalents	77,380	(13,827)
Cash and cash equivalents, at beginning of period	34,024	63,711
Cash and cash equivalents, at end of period	$ 111,404	$ 49,884