CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 181,650	$ 120,129
Adjustments to net income:
Depreciation and amortization	221,603	105,828
Income from discontinued operations	(51,115)	(12,266)
Amortization of share-based compensation	14,235	7,780
Non-cash rental revenue adjustments	(3,862)	(2,096)
Amortization of net premiums on mortgages payable	(6,959)	(278)
Amortization of deferred financing costs	6,682	4,759
Other non-cash adjustments		(301)
Cash provided by discontinued operations	5,257	9,984
Change in assets and liabilities:
Accounts receivable and other assets	1,481	3,594
Accounts payable, accrued expenses and other liabilities	(23,305)	(28,605)
Net cash provided by operating activities	345,667	208,528
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of investment properties, net of cash received	(1,286,384)	(650,627)
Improvements to real estate, including leasing costs	(5,902)	(4,501)
Proceeds from sales of real estate:
Continuing operations	8	23
Discontinued operations	98,768	34,283
Loans receivable	(10,551)
Restricted escrow deposits for Section 1031 tax-deferred exchanges and pending acquisitions	(7,344)	(4,753)
Net cash used in investing activities	(1,211,405)	(625,575)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash distributions to common stockholders	(298,544)	(175,719)
Cash dividends to preferred stockholders	(31,447)	(28,962)
Borrowings on line of credit	2,096,300	908,000
Payments on line of credit	(1,785,900)	(536,400)
Proceeds from notes payable issued	750,000
Principal payment on notes payable	(100,000)
Principal payments on mortgages payable	(16,207)	(11,171)
Proceeds from term loan	70,000
Proceeds from common stock offering, net	755,085
Proceeds from preferred stock offerings, net		395,377
Redemption of preferred stock		(127,500)
Repayment of ARCT line of credit	(317,207)
Repayment of ARCT term loan	(235,000)
Distributions to noncontrolling interests	(751)
Debt issuance costs	(9,150)	(7,069)
Proceeds from dividend reinvestment and stock purchase plan, net	3,827	2,159
Other items	(10,556)	(3,039)
Net cash provided by financing activities	870,450	415,676
Net increase (decrease) in cash and cash equivalents	4,712	(1,371)
Cash and cash equivalents, beginning of period	5,248	4,165
Cash and cash equivalents, end of period	$ 9,960	$ 2,794