CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 71,813	$ 39,263
Adjustments to net income:
Depreciation and amortization	69,808	34,578
Income from discontinued operations	(39,480)	(2,216)
Amortization of share-based compensation	3,845	2,956
Amortization of net premiums on mortgages payable	(1,947)	(97)
Cash provided by discontinued operations	1,496	2,351
Change in assets and liabilities:
Accounts receivable and other assets	(1,961)	(166)
Accounts payable, accrued expenses and other liabilities	(47,300)	(26,343)
Net cash provided by operating activities	56,274	50,326
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of investment properties, net of cash received	(100,051)	(7,854)
Improvements to real estate, including leasing costs	(1,678)	(1,059)
Proceeds from sales of real estate, discontinued operations	59,459	3,559
Loan receivable	(9,587)	(1,695)
Restricted escrow deposits for Section 1031 tax-deferred exchanges and pending acquisitions	(37,353)	(2,239)
Net cash used in investing activities	(89,210)	(9,288)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash distributions to common stockholders	(84,977)	(58,192)
Cash dividends to preferred stockholders	(10,482)	(8,216)
Borrowings on line of credit	782,600	122,000
Payments on line of credit	(824,000)	(316,400)
Principal payment on notes payable	(100,000)
Principal payments on mortgages	(1,112)	(10,806)
Proceeds from term loan	70,000
Proceeds from common stock offering, net	755,495
Proceeds from preferred stock offering, net		360,941
Redemption of preferred stock		(127,500)
Repayment of line of credit, previously belonging to ARCT	(317,207)
Repayment of term loan, previously belonging to ARCT	(235,000)
Distributions to noncontrolling interests	(115)
Debt issuance costs	(273)
Proceeds from dividend reinvestment and stock purchase plan, net	811	743
Other items	(3,893)	(2,579)
Net cash provided by (used in) financing activities	31,847	(40,009)
Net (decrease) increase in cash and cash equivalents	(1,089)	1,029
Cash and cash equivalents, beginning of period	5,248	4,165
Cash and cash equivalents, end of period	$ 4,159	$ 5,194