CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Statement of Cash Flows [Abstract]
Net cash provided by operating activities:	$ 103,721	$ 95,158
Cash flows from investing activities:
Acquisition of real estate, including intangible assets	(51,962)	(81,535)
Investment in real estate under construction	(69,073)	(34,808)
Capital expenditures	(5,403)	(33,532)
Net proceeds from sale of properties	33,226	47,236
Principal payments received on loans receivable	1,104	1,194
Investment in loans receivable	(20,833)	(16,967)
Distributions from non-consolidated entities in excess of accumulated earnings	876	15,440
Increase in deferred leasing costs	(6,519)	(4,919)
Change in escrow deposits and restricted cash	(2,610)	(2,337)
Real estate deposits, net	(37)	(1,259)
Net cash used in investing activities	(121,231)	(111,487)
Cash flows from financing activities:
Dividends to common and preferred shareholders	(78,343)	(68,233)
Conversion of convertible notes	(62)	(2,663)
Principal amortization payments	(20,971)	(23,442)
Principal payments on debt, excluding normal amortization	(163,267)	(338,537)
Change in credit facility borrowings, net	(48,000)	0
Proceeds from senior notes	249,708	247,565
Proceeds from term loans	99,000	64,000
Increase in deferred financing costs	(3,215)	(6,539)
Proceeds of mortgages and notes payable	27,790	40,000
Change in restricted cash	0	(1,573)
Cash distributions to noncontrolling interests	(2,186)	(1,978)
Redemption of noncontrolling interests	(1,962)	0
Repurchase of preferred shares	0	(155,004)
Issuance of common shares, net	10,861	302,987
Net cash provided by financing activities	69,353	56,583
Change in cash and cash equivalents	51,843	40,254
Cash and cash equivalents, at beginning of period	77,261	34,024
Cash and cash equivalents, at end of period	$ 129,104	$ 74,278