CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 126,560	$ 82,671
Adjustments to net income:
Depreciation and amortization	147,280	69,093
Income from discontinued operations	(43,562)	(7,562)
Amortization of share-based compensation	7,498	5,550
Amortization of net premiums on mortgages payable	(4,441)	(168)
Other non-cash adjustments		(301)
Cash provided by discontinued operations	2,777	5,489
Change in assets and liabilities:
Accounts receivable and other assets	(2,424)	1,820
Accounts payable, accrued expenses and other liabilities	(12,255)	(659)
Net cash provided by operating activities	221,433	155,933
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of investment properties, net of cash received	(748,374)	(219,554)
Improvements to real estate, including leasing costs	(3,294)	(2,405)
Proceeds from sales of real estate:
Continuing operations	8
Discontinued operations	76,333	18,549
Loans receivable	(9,584)	(3,795)
Restricted escrow deposits for Section 1031 tax-deferred exchanges, pending acquisitions and other deposits	(14,448)	(6,449)
Net cash used in investing activities	(699,359)	(213,654)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash distributions to common stockholders	(191,669)	(116,552)
Cash dividends to preferred stockholders	(20,965)	(18,480)
Borrowings on line of credit	1,533,200	377,400
Payments on line of credit	(990,200)	(431,200)
Principal payment on notes payable	(100,000)
Principal payments on mortgages	(2,674)	(10,952)
Proceeds from term loan	70,000
Proceeds from common stock offering, net	755,136
Proceeds from preferred stock offerings, net		395,377
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	(287)
Debt issuance costs	(511)	(7,058)
Proceeds from dividend reinvestment and stock purchase plan, net	1,912	1,548
Other items	(6,482)	(2,963)
Net cash provided by financing activities	495,253	59,620
Net increase in cash and cash equivalents	17,327	1,899
Cash and cash equivalents, beginning of period	5,248	4,165
Cash and cash equivalents, end of period	$ 22,575	$ 6,064